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LIBRARY OF CONGRESS. 

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UNITED STATES OF AMERICA. 



Brick for Street Pavements. 



AN ACCOUNT OF TESTS MADE OF BRICKS AND PAVING 
BLOCKS, WITH A BRIEF DISCUSSION OF STREET 
PAVEMENTS AND THE METHOD OF CON- 
STRUCTING THEM. 



BY 



M. D. BURKE, C.E. 



CONTENTS. 



le Samples Submitted for Testing 

Jiow the Specimens were Prepared 7 

Description of Specimens Submitted 9 

How the Tests were Made 14 

Abrasion and Impact 16, 42 

Description of the Tables 27 

The Chemistry of Brick Manufacturing 36 

Discussion of the Tests 38 

The Absorption Tests 40 

Transverse Strength 41 

Statistics of Traffic and Durability of Pavements 43 

The Probable Durability o^a Brick Pavement , . 47 

Municipal Methods 48 

General Discussion of Pavements 53 

What Shall be Specified 61 

What Has Been Done 68 

The Matrix 76 

Where Should Brick be Used for Street Pavements 78 

Maintenance 

What is in a Name S3 

Size of Paving Brick 84 



Brick for Street Pavements. 



AN ACCOUNT OF TESTS MADE OF BRICKS AND PAVING 
BLOCKS, WITH A BRIEF DISCUSSION OF STREET 
PAVEMENTS AND THE METHOD OF CON- 
STRUCTING THEM. 



BY 

M. D. BURKE, C.E. 



APR 9 ) . 



/if^X 



O"' 



CINCINNATI : 
ROBERT CLARKE & CO. 

1892. 

a 



TE^55" 



Copyrighted, 1892. 
By KOBERT CLARKE & CO. 




0(o-^^173 



PREFA^CE. 



A large part of the contents of this pamphlet was con- 
tained in a report made to the village authorities of tests of 
material to be used in paving streets in Avondale, where the 
writer was employed as village engineer. The investiga- 
tion then made was as thorough as the time and means at 
hand would justify. Inquiries for the results of the work 
have been so numerous, and requests for the same have been 
so frequently repeated, that it has been deemed advisable to 
publish the work in this form. 

If any information or suggestions herein contained shall 
aid in the construction of better pavements, or prevent the 
waste of money upon bad ones, or shall bring people to a 
consideration of placing municipal improvements under sys- 
tematic control and direction, or shall cause manufacturers 
to see that their true interest will best be subserved by plac- 
ing only good material upon the market, then this little 
pamphlet will have served a useful purpose. 

x\I. D. BURKE. 

Cincinnati, March 16, 1892. 



BRICK FOR STREET PAVEMENTS, 



The Samples Submitted for Testing. 
It having been decided that the Main Avenue pavement 
should be constructed of some form of clay product, a series 
of tests of the various materials in market was deemed ad- 
visable in order to aid in selecting the proper variety, and, if 
found practicable, fix a standard by which the difiterent va- 
rieties might be adjudged and accepted or rejected, as their 
qualities and powers of resistance would determine. Ac- 
cordingly a circular letter was addressed to manufacturers 
and dealers, requesting them to ship to my office, at 41 Pike 
Building, Cincinnati, Ohio, samples consisting of twenty or 
more of each of the varieties of the bricks or blocks manu- 
factured or sold by them for street paving purposes, to be 
tested. In response to the circular letter, samples were 
kindly furnished by the following parties, and numbered as 
below : 

1. Lithonia Georgia Granite, John Regan, contractor, 
city. 

2. West Virginia Brick Co., Charleston, W. Va., H. C. 
Bruce, President. 

3. The Diamond Brick and Terra Cotta Co., Kansas 
City, Mo. 

4. The Pittsburg Sewer Pipe and Fire Clay Co., ^ew 
Brighton, Pa. 

5. Canton Brick Co. (red granite street pavers). Canton, 

Ohio. 

(51 



b BRICK FOR STREET PAVEMENTS. 

6. The Royal Brick Co. (iron rock pavers), Canton, O. 

7. Purington Paving Brick Co., Galesbnrg, 111. 

8. The United States Fire Clay Co., :N'ew Lisbon, Ohio ; 
M. li. Coney, agent. 

9. The Middleport Granite Brick Co. (Halhvood Block), 
Middleport, Ohio. 

10. L. B. Townsend & Co. (Townsend Paver), Zanesville, 
Ohio. 

11. The Brazil Paving Block, Brazil, Ind., L. H. xMc- 
Camnion Bros., agents. 

12. The Jones Paving Block, Zanesville, Ohio, L. H. 
McCammon Bros., agents. 

13. The Ohio Paving Co. (Halhvood Block), Columbus, 
Ohio. 

14. The John Porter Co., IsTew Cumberland, W. Ya. 

15. The l^ew York Paving Brick Co., Syracuse, K. Y. 

16. Hallwood Block Granite Brick, manufactured by 
Tennessee Paving Brick Co., Bobbins, Tenn. 

In this report the varieties are represented by the numbers 
above given, and the separate specimens by letters. Of each 
variety, except 'Nos. 1 and 16, ten bricks or blocks were used 
in making the various tests. A number always indicates the 
same variety, but only when the number and letter are the 
same, does it mean the same brick. Thus ISTo. 1 always 
means a granite block, yet IsTo. 1 A and No. 1 E are differ- 
ent blocks, but both Georgia granite. 

It was deemed advisable to ascertain, first, the essential 
chemical ingredients; second, the ratio of absorption ; third, 
crushing strength; fourth, transverse strength; fifth, the re- 
sistance to abrasion and impact. The Riehle testing ma- 
chine of Messrs. Otten & Westenhofl, appearing to be the 
most readily available, these gentlemen were employed, not 
only to make the crushing and transverse tests, but also to 



BRICK FOR STREET PAVEMENTS. < 

make the chemical analysis and determine the specific grav- 
ity and ratio of absorption of the cubes which were pre- 
pared for the crushing test. 

How THE Specimens were Prepared. 

The testing of a single specimen of any kind being 
deemed insufficient, it was determined that three cubes of 
each variety be prepared for ascertaining the crushing 
strength. Accordingly three bricks or blocks of each va- 
riety were taken at random, and sent to the marble works of 
Joseph Foster & Sons, placed in the mill and sawed in tw^o 
lengthwise, the cut being made so as to leave one piece about 
2J inches in width. This piece was then cut by the saws trans- 
versely, so as to approximate as nearly as practicable to a 
2-inch cube from the interior of the brick. The roughly 
sawn cubes were then placed upon a rubbing bed and worn 
down to the required size, with parallel and equal faces. 
Three such cubes were made of each variety. Of the gran- 
ite, A and B were made from one block; C from another, 
dumber 16, the three cubes were made from a single block, 
as of this number but three blocks were furnished. In 
making ITo. 15, which is of a very refractory material, the 
saw was unfortunately deflected in such a manner that 
•cubes could not be obtained from two of the pieces, B and 
C, and they were rubbed down to two inches square by IJ 
inches high. 

Subsequent developments show that it would have been 
advisable to have made IJ inch cubes instead of 2 inch. The 
testing machine used has a capacity of 52,000 pounds. Tt 
was thought that very few, if any, of the specimens would 
show an ultimate crushing strength exceeding 13,000 pounds 
per square inch, but in this we were mistaken. 

By the same process above described, four " granite 



8 BRICK FOR STREET PAVEMENTS. 

bricks" were manufactured; that is, four pieces of granite 
2Jx4x8 inches were made, to be subjected to the same tests- 
as the bricks, in order to compare the resistance of the chiy 
products with a standard paving material. Tt will be ob- 
served that great care was taken in this work m order to 
preserve the material of each specimen intact and to pre- 
vent injury to it in any way. No cutting with chisels or 
spalling was permitted. Each specimen was numbered and 
lettered and its identity preserved throughout the entire 
series of tests. The cubes were used for three purposes : 
First, for obtaining the ratio of absorption ; second, specific 
gravity, and third, the crushing strength of the material. 
Another absorption test was made with whole bricks, and 
in some instances the percentages obtained differed materi- 
ally. There are two reasons for these differences : A single 
cube only was used and it was immersed but twelve hours. 
For some of this material probably this length of time was 
too short for it to absorb all the water that it would ulti- 
mately take up, but generally the percentages obtained by 
immersing the cubes was materially higher than that ob- 
tained from the whole bricks, which is a result to be ex- 
pected when it is remembered that the outer portions of 
the bricks were in several cases salt-glazed and were gener- 
ally more dense and burned harder than the interior portion 
from which the cubes were obtained. The specimens sub- 
jected to crushing were lettered A, B, C, those lettered A 
being used for the absorption as well as the crushing test. 

^o essential preparation of the specimens for the re- 
maining tests was necessary, They were all kept in a steam- 
heated room from the time of their arrival until used, which 
was about one week for the latest arrivals, and about four 
weeks for the earliest. All would be classed as perfectly 
dry. All adhering sand or dust was carefully brushed from 



BRICK FOR STREET PAVEMENTS. 9 

tliose tested for absorption or abrasion before weighing them. 
In selecting those used for ascertaining the transverse 
strength, perfect specimens, showing no fire cracks or other 
defects, were taken. In fact the manufacturers or agents 
had generall}^ done the selecting and packing with such care 
that no outside defects were visible, except as noted for 
No. 10. 

Description of Specimens Submitted. 

No. 1. Application was made to the Southern Granite 
Company for specimens of their material, but none was re- 
ceived, accordingly the samples used were obtained from Mr. 
John Regan, contractor, who was using Lithonia granite in 
paving a street, and the cubes and specimen bricks were 
sawed from the interior of the blocks, rubbed down, with- 
out the use of hammer or chisel, to the dimensions given 
as above noted, in the preparation of the specimens. 

No. 2 is a hard burned brick manufactured from plastic 
clay and burned in the ordinary clamp kiln. It is about 
2J''x3f"x8'', and if closely laid, about sixty-iive of them 
would pave a square yard. Its record can be traced through 
the various tests in the following tables by its number. Its 
history as a street paver is said to be quite satisfactory in 
some localities, but it should not be used where the traffic is 
very considerable. 

No. 3 is manufactured from a shale or plastic clay which 
readily vitrifies. In size it averages 2J"x3f^^x8'', and about 
sixty- eight will be required for each square yard of pave- 
ment. The chemical analysis, as given in table No. 1, does 
not show that it contains an objectionable amount of lime, 
but other tests unmistakably manifest its presence in form 
and quantity to a highly detrimental degree. The brick is 
very hard and dense, ranking third in specific gravity, but it 
is rather small and quite brittle, the fracture being con- 



10 BRICK FOR STREET PAVEMENTS. 

choidal, and it will yield to the trituration of animals' shoes 
rather than the grinding of the wheels of vehicles. I have 
no knowledge of its record in actual service as a street 
paver. 

IN'o. 4 is what is known as a lire-clay brick. In color it 
is an orange buff. The average size is 2J''x4J''x8J^'. About 
tifty-nine would lay a square yard of pavement. It absorbs 
water rather freely, but not to a greater extent than many 
acceptable building stones, and in all the other tests its stand- 
ing is good. 

Nos. 5 and 6 are practically the same brick, manufac- 
tured from a shale or indurated clay. In color they are a dark 
red. They average 2J''x4i"x8f'', and about fifty-nine of 
them will pave a square yard. The samples tested are all 
burned quite hard, but not in all cases to vitrification ; hence 
while they show great transverse strength, and resist abra- 
sion well, they are comparatively low in crushing strength 
and there is great variation in the percentage of absorption. 
Their record in actual use is quite satisfactory, but I have 
no statistics of the severity of the traffic to which they have 
been subjected. 

No. 7 is of a dark red color, 2J''x3f"x7}'' in size. About 
sixty-nine will be required for each square yard of pave- 
ment. In all the tests this ranks among the best of the red 
bricks, and its record under moderate traffic is good. An 
increase in size so as to afford a greater weight of pavement 
would appear to be prudent if it is to be used under heavy 
traffic. 

^o. 8 is a fire-clay brick of a light buff color, 2^q''k 
3||.''x8^V'' ^^ which about fifty-five will pave a square yard. 
The material of which it is composed has not been very 
finely ground nor very thoroughly compressed. As a con- 
sequence it has a low specific gravity, a moderately high rate 



BRICK FOR STREET PAVEMENTS. 11 

of absorption, and is outranked by several other varieties in 
the other tests, but in the uniform quality of each individual 
brick as compared w^ith the others of its kind, it stands at 
the head of the list. 

^o. 9. In chemical constituents this coincides more 
nearly with No. 2 than any of the other samples submitted, 
yet the treatment of the material has been so different that 
the results are in no respect similar. It is a glazed Hall- 
^vood block, 2^''x3|''x8j'', and about fifty-five of them will 
lay a square yard of pavement. The glaze is said to be a 
natural, and not a salt glaze. The corners are rounded to 
about one-half inch radius, and two J" groves extend length- 
wise around the block near its middle. The clay has been 
finely ground and completely vitrified, but inasmuch as it 
contracts greatly in burning, the blocks are liable to show 
cracks on the outside or cavities on the inside. When 
broken the blocks show an even dense texture of a dark 
brown color, and, were the defect above noted remedied 
(which it would appear to the writer, could be readily done), 
they would be greatly improved for street paving purposes. 

No. 10 had been assorted to some extent when they came 
into my hands, as more than one-fourth of the bricks had 
been broken in the box. The average size ^s 2^-^'^x4^'xS^^^^y 
and fifty-eight of them will lay a square yard of pavement. 
They are dark brown in color, with corners rounded to 
-about one-fourth of an inch radius; burned exceedingly 
hard, although they do not present the melted appearance 
of most of the vitrified bricks. While this brick has great 
hardness, with sufficient density for all practical purposes, 
and even a high degree of tenacity under a steadily applied 
stress, yet it possesses great brittleness, and when subjected 
to shocks, shows a tendency to spall badly. Could the qual- 
ity of toughness be given it without materially diminishing 



12 BRICK FOR STREET PAVEMENTS. 

its liardiiess, no essential of a desirable brick paver w^ould be 
lacking. 

Ko. 11 is manufactured from a clay found in the coal 
measures but not termed a Hre-clay. It is a salt-glazed 
block 2|"x4''x9J'' in size, and each square yard of pavement 
will require about forty-eight blocks. The corners are 
slightly rounded. Little fault can be found w^ith the chem- 
ical ingredients, although an additional amount of iron 
would be in better proportion to the quantity of alkalies 
present. The form and size of block has been well chosen. 
if such a thickness can be properly burned, but the mechan- 
ical work of preparing the material and forming the block 
has been inditferently done and the burning decidedly un- 
derdone. 

Xo. 12, is of well chosen dimensions, being 2f''x4J''x9",. 
and Hfty-one blocks will lay a square yard of pavement. The 
material of which it is composed is about the same as that of 
which JSTo. 10 is made, namely, a mixture of shale and clays 
found in the coal measures. The corners are rounded to 
about one-fourth of an inch radius. The blocks are re- 
pressed, with live grooves passing transversely nearly across 
one side, and eight diagonally nearly across the other. The 
sand, or possibly the oil, used in repressing, serves to give 
it a reddish brown color. Giving the block a form such 
that it should always be placed with the same side up ap- 
pears to be a relinenient hardly required in practice. The 
material might have been made into a good paving block, 
but it was not. The clays were not ground sufhciently fine^ 
neither was the burning carried to such an extent as to pro- 
duce a block that would withstand the abrasion of street 
trafhc. The samples tested were obtained from an agent, 
and not directly from the manufacturers. 

No. 18, is salt-glazed, corners rounded to about one-half 



BRICK FOR STREET PAVEMENTS. 13 

inch radius, with two grooves ahout one and one-half inches 
apart, passing lengthwise around it near the middle. Ahout 
forty-six blocks will pave one square yard. It shows a 
higher percentage of iron than any other specimen analyzed, 
but appears to be mainly composed of a plastic clay, possi- 
bly indurated, Avhich has been finely ground and skillfully 
combined. In the process of burning or vitrification, the 
iron and alkalies have combined so as to render the material 
practically impervious to moisture, but it has not quite as high 
a specific gravity nor the strength that should be obtained 
with this material. Its record in practical use is very good, 
and under any thing like fair treatment will give satisfactory 
results. 

1^0. 14, is a repressed fire-clay brick, wnth corners 
rounded to about three-sixteenths of an inch radius. The 
average size is 2J''x4J''x8J'', and sixty of them will pave 
a square yard. The material is very similar to ]^o. 4, but 
the repressing has given it advantages in some particulars. 
It is of a buff color. It has been used as extensively for 
street paving as any other variety tested, and under mod- 
erate trafiic its record has been satisfactory. A result ap- 
pears to be attainable with this material which is not al- 
ways secured, but when it is, leaves but slight room for ap- 
parent improvement in the manufacture of paving blocks. 
It is obtained by the fusion of the iron with the silica when 
acted upon by the alkalies or other fluxes, in the pro- 
cess of burning or vitrification, producing a block, which, 
when broken, presents a gray metallic or granitic texture, 
showing no traces of cleavage or granular structure, and 
perfectly uniform throughout. Of the sample bricks of this 
variety tested, about seventy-five per cent were completely 
vitrified as here described, while the others presented a 
granular appearance, either throughout or in the central por- 



14 ' BRICK FOR STREET PAVEMENTS. 

tion, but they were all very hard burned. The cube used 
for obtaining specific gravity and percentage of absorption 
was but partially fused, hence it shows great affinity for 
moisture. This fusion does not appear to add materially ta 
.the strength, but it does lessen the amount of absorption 
without materially increasing the brittleness. 

-N'o. 15, is drab or brown in color, 2J''x3Yyx7|'' in 
size, requiring about seventy-five of them to lay a square 
3'ard of pavement. The clay from which this brick is made 
is evidently largely formed from the disintegration of lime- 
stone rocks. All the samples were thoroughly vitrified, and 
the product is an exceedingly refractory substance. Could 
the lime be eliminated from it before burning, the bricks- 
would be as nearly indestructible as could be desired, but 
every brick tested manifested the presence of lime in quan- 
tity sufficient to impair its durability. 

J^o. 16, is made from a shale or clay found in the coal 
measures, although not described as a fire clay. But three 
of these blocks were obtained for making the tests, and 
each was quite a perfect specimen of its kind. This is a 
Hallwood block, corresponding in dimensions with E'o. 13^ 
and if the samples fairly represent the product of the kilns, 
pavements properly laid with this material will be both dura- 
ble and satisfactory. 

How THE Tests Were Made. 

Absorption. — Of the cubes prepared as before described, 
the one lettered "A" of each variety was placed in a drying 
oven and maintained at a temperature of 212° Fahrenheit 
for twelve hours, in order to drive off any contained mois- 
ture. Each was then accurately weighed. The figures ob- 
tained are found in the second column from the left of 
Table Xo. 2. It was then immersed in water, where it re- 



BRICK FOR STREET PAVEMENTS. 15 

mained for the succeeding twelve hours, when it was taken 
out, the adhering moisture wiped off, and again weighed, the 
results being noted in the third column from the left in the 
same table. At this time it was also weighed in water, these 
last weights being found in the sixth cohimn of Table 
No. 2. 

For a further test of absorption two whole bricks of each 
variety (except as noted in the table) were selected at ran- 
dom, lettered G and H respectively, placed on an ordinary 
counter scale weighing to quarter ounces, the results noted, 
and are found in the ninth column from the left in table 
No. 2. They were then placed in water and kept entirely 
submerged for seventy hours, wdien they were taken out, 
dried with a towel, again weighed, with results found in the 
tenth column of the same table. These results are only as 
accurate as the scales were, but the test can be readily re- 
peated at any time, and will give a fair practical measure of 
the absorption to be expected from whole bricks in a sim- 
ilar length of time. The samples had been kept in a steam- 
heated room during the preceding ten days, and the dust and 
sand were carefully brushed from them before the first 
w^eighing. 

Cnishing Strength. — For determining the crushing 
strength tlie cubes were carefully measured, their upper and 
lower surfaces protected by a thickness of blotting paper, 
and they were subjected to pressure in a Riehle Testing Ma- 
chine of 52,000 pounds capacity. The results obtained will 
be found in table No. 3. No visible effect was produced 
upon the granite except that " B" was very slightly spalled, 
as noted. No. 15 " C," which was about one and one-half 
by two inches, was set on edge after being tried the other 
way, and a pressure exerted exceeding 17,000 pounds per 



16 • BRICK FOR STREET PAVEMENTS. 

square inch, but it could not be crushed, althougli it spalled 
at one corner at a little over 7,000 pounds per square inch. 

Transverse Strength. — The transverse strength was as- 
certained in the same machine in the following manner : 
Three bricks of each variety (except as noted) were chosen 
and lettered D, E and F. The lower knife edges were ad- 
justed at precisely six inches apart, the upper knife edge 
being placed centrally between them. Each specimen was 
carefully measured and its surface protected from direct 
abrasion at the points of bearing by two or three thick- 
nesses of blotting-paper, and the weight required to break 
it carefully noted. These results are found in table Xo. 4. 

Abrasion and Impact. 
The method adopted for determining the relative re- 
sistance to abrasion and impact was that whicli is com- 
monly known as the rattling test. A cylinder about six 
feet in leno^th bv twentv-eis^ht inches in diameter, contain- 
ing pieces of cast iron, varying in weight from one to six 
or eight pounds, and in the condition in which it is ordina- 
rily used for cleaning castings, was selected for this purpose. 
Four bricks of each variety (with the exceptions noted in the 
table) were selected and lettered G, H, I and J, two of the 
specimens, G and H, having been soaked for the preceding 
seventy hours. The specimens were carefully weighed and 
all placed in the rattler at one time. Billets of wood were 
put in with them, as is ordinarily done in cleaning cast- 
ings, to prevent breaking. The cylinder was revolved at a 
speed of about twenty-four revolutions per minute, and at 
the end of one thousand revolutions was stopped, the speci- 
mens taken out, weighed and the loss of each noted. The 
object of making this :^rst test in this particular manner 
was to wear away the sharp angles or corners and bring 



BRICK FOR STREET PAVEMENTS. 17 

each piece as nearly as practicable on a level footing with 
its fellow for that which was to follow. This first test, 
therefore, was intended more to equalize the several pieces 
than to measure their actual wear. 

On the following day the specimens were again placed 
in the cleaner, omitting the protecting billets of wood. The 
object now being to observe the survival of the fittest. 
The cylinder was given three thousand revolutions, occupy- 
ing something over two hours in time, and although all the 
pieces were in at the same time, excepting a fragment of J^o. 
15 " I," which had broken ofiT in the former test and was in- 
advertently omitted ; there was ample room for motion and 
the loss in weight of every piece was a measurable quantity. 
The individuality of some specimens was lost, as the marks 
were in some cases almost entirely worn away, but there was 
no trouble in identifying the varieties ; hence, in tabulating 
the results of this work the percentage of loss in the sec- 
ond rattler test is given for each variety. This will be found 
in detail in table 'No. 5. 

With the completion of the second rattler test closed 
the actual work upon the specimens, and the labor of col- 
lating the information obtained was commenced. Further 
investigation would appear to be desirable, especially some 
test that will more nearly resemble the attrition of the shoes 
of animals in passing over the pavement than do any of the 
tests that were made. But the information now gained 
would appear to justify seeking that knowledge by a prac- 
tical test of the brick in the street pavement itself. 
2 



18 



BRICK FOR STREET PAVEMENTS. 



TABLE No. 1.— Chemical Analyses. 





< 


< 




c4 


s 
% 


1 
< 

< 


II 




2 


73.32 


14.82 


8.34 


0.70 


0.99 


2.26 





100.43 


3 


64.37 


19.73 


9.07 


0.82 


2.32 


1.89 


1.80 


100.00 


4 


67.36 


22.05 


5.61 


0.86 


0.36 


2.70 


1.06 


100.00 


5 


67.65 


18.36 


8.34 


0.80 


1.02 


2.58 


1.25 


100.00 


6 


68.12 


18.63 


8.53 


0.68 


0.71 


2.58 


0.75 


100.00 


7 


68.69 


17.95 


7.25 


0.76 


1.47 


2.83 


1.05 


100.00 


8 


64.08 


25.32 


5.44 


0.30 


0.29 


0.63 


3.94 


100.00 


9 


71.57 


17.06 


8.34 


0.50 


0.58 


0.56 


1.39 


100.00 


10 


61.80 


20.76 


8.70 


1.38 


1.09 


1.44 


4.83 


100.00 


11 


77.67 


14.77 


3.63 


0.38 


0.27 


2.43 


0.85 


100.00 


12 


65.08 


22.39 


7.97 


0.62 


0.74 


2.33 


0.87 


100.00 


13 


66.30 


18.62 


9.78 


0.40 


0.84 


1.89 


2.17 


100.00 


14 


69.02 


22.07 


4.53 


1.70 


0.38 


1.34 


0.96 


. 100.00 


15 


67.67 


11.67 


6.53 


12.74 


0.95 


0.80 




100.36 


16 


70.57 


15.19 


7.97 


0.78 


0.32 


1.15 


4.02 


100.00 



Undertermined is water manganese oxide and possibly some titanic acid. 

OTTEN & WESTENHOFF, 

Chemists. 



BRICK FOR STREET PAVEMENTS. 



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20 



BRICK FOR STREET PAVEMENTS. 



TABLE No. 3.— Crushing Strength. 



i 




SIZE IN INC. 


z5 


<i 


r- 03 S 
< Q O 




'^fi| 






!z; 






ii 


p. z 


ag5 


R ^ 


aSS 










H 
g 


a 


^ 


.c 


^ 


iJ o 


-h 


s o 


so a 


REMARKS. 






&4 








5 < 


I-; ch 


►J ^ 05 


CC &H 


cc Ah yj 








1 


'a 


C 

a 






< 

Ph z 




gz 

O -1 


i-i 






1 


B 


2. 


2. 


2. 


4. 


40480 


■ 
10120 






Did not crush at 52000 lbs.= 


=13000 ]b>. 




















per D". 




2 


A 


1 97 


1.97 


1.94 


3 82 


29600 


7749 


35500 


9293 


Soaked 12 hours. 




2 


B 


1.94 


1 94 


1.94 


3.76 


28000 


7447 


35920 


9553 






2 


C 


1.94 


1.97 


1.94 


3 82 











Did not spall at 52000 lbs. = 
per D". 


13613 lbs. 


3 


A 


1.97 


1.97 


1.97 


3.88 


32290 


8322 


37720 


9722 


Soaked 12 hours. 




3 


B 


I 94 


1 97 


1 94 


3,82 


15200 


3979 


■48000 


12565 






3 


C 


1 97 


1.94 


1.94 


3.76 


18100 


4813 


32720 


8702 






4 


A 


1.97 


1.97 


1.97 


S 88 


33110 


8533 


43120 


11113 


Soaked 12 hours. 




4 


B 


1,97 


1 97 


1 97 


3,88 


36590 


9427 






Did not crush at 52000 lbs. = 
perQ". 


13402 lbs. 


4 


c 


1.97 


1.97 


1 97 


3,88 










Did not spall at 52000 lbs. = 

per D". 


13402 lbs. 


5 


A 


1.94 


1.97 


1.94 


3 82 


50000 


13089 






Soaked 12 hours. Did not 
52000 lbs. = 13613 lbs. per Q 


crush at 


5 


B 


1 97 


1.97 


1.97 


3,88 


3S8oO 


10013 


391.50 


10090 






5 


C 


1 97 


1.97 


1 97 


3.88 


28000 


7216 


38850 


10(113 






6 


A 


1.94 


1 91 


1 91 


3 6.i 


19650 


5383 


23100 


6329 


Soaked 12 hours. 




6 


B 


1.94 


1 94 


1 91 


3.70 


37220 


10059 


51500 


13919 






6 


C 


1.97 


2.00 


1.97 


3 94 










Did not spall at 52000 lbs. = 
perD". 


13198 lbs. 


7 


A 


2.00 


1.97 


1.97 


3.88 


25120 


6471 


51600 


13300 


Soaked 12 hours. 




7 


B 


1.97 


1,97 


1.97 


3.88 






. 




Did not spall at 52000 lbs. = 
per D'^ 


13402 lb.s. 


7 


C 


1.97 


1 97 


1 97 


3.88 


38550 


9935 


52000 


13402 






8 


A 


1 97 


1.97 


1 94 


3.82 


34000 


8900 


46460 


12162 


Soaked 12 hours. 




8 


B 


1 97 


1.97 


1.94 


3.82 


25220 


6602 


446.50 


11688 






8 


C 


1.97 


1.97 


1.97 


3.88 


25030 


6451 


39570 


10198 






9 


A 


1.97 


1.97 


1 94 


3 82 


24000 


6283 


39820 


10424 


Soaked 12 hours. 




9 


B 


1 97 


2.12 


1.97 


4.18 


26000 


6220 


48270 


11.548 






9 


C 


2.00 


1 97 


1.94 


3.82 


17500 


4581 


39820 


10424 






10 


A 


1.97 


1 97 


1.97 


3.88 


50750 


13080 






Soaked 12 hours. Did not 
52000 lbs. = 13402 lbs. per D 


crush at 


10 


B 


1 97 


1.97 


1 97 


3.88 


35500 


9149 


51460 


13263 






10 


C 


1 97 


1.97 


1.94 


3 82 


32000 


8377 


50050 


1.3102 






11 


A 


1.97 


1,97 


197 


3.88 


27900 


7191 


50300 


12964 


Soaked 12 hours. 




11 


B 


1 97 


1.97 


1.94 


3 82 


24000 


6283 


39400 


10314 






n 


C 


1.97 


1.97 


1.97 


3.88 


23880 


6155 


27250 


7023 






12 


A 


1.97 


1.94 


1.94 


3 76 


19700 


5239 


37330 


9928 


Soaked 12 hours. 




12 


B 


1 97 


1.97 


1.97 


3.88 


14240 


3670 


17620 


4541 






12 


C 


2.00 


1.97 


1 94 


3.82 


10960 


2869 


28110 


7359 






13 


A 


1.91 


1 97 


1 97 


3 88 


28000 


7216 


48000 


12371 


Soaked 12 hours. 




13 


B 


1.97 


1 97 


1 97 


3.88 


40000 


10309 


46600 


12010 






13 


C 


1 94 


1.97 


I 91 


3.76 


1'.I500 


5186 


3S380 


10207 






14 


A 


1 97 


1.97 


1.97 


3.8- 


38800 


10000 


50770 


13085 


Soaked 12 hours. 




14 


B 


1 97 


1.97 


1.97 


3.88 










Did not spall at 52000 lbs. = 
per D". 


13402 lbs. 


14 


C 


1.97 


1 97 


1 94 


3.82 










Did not spall at 52000 lbs. = 

per D"- 
Soaked 12 hours. Did not 


13613 lbs. 


15 


A 


1 97 


1 97 


1,97 


3.8S 


27770 


7157 






crush at 






















52000 lbs. = 13402 lbs per n 


" 


15 


B 


1 50 


1 97 


1,97 


3 88 










Did not spall at 52000 lbs. = 
per D". 


13402 lbs. 


15 


C 


1.50 


2.03 


1.94 


3 94 










Did not spall at 52000 lbs. = 


13198 lbs. 


















per D". 




15 


C 


1 94 


2 03 


1.50 


3.04 


a5400 


11644 






Did not crush at 52000 lbs, = 
ner n". 


17105 lbs. 


16 


A 


2. 


2. 


2. 


4 00 


51660 


12915 






Soaked 12 hoiars. Did not crush at 52000 






















lbs. = 13000 lbs. per D". 




16 


B 


2. 


1.97 


I 97 


3.88 










Did not spall at 52000 lbs. = 
per D". 


13402 lbs. 


16 


C 


2. 


2. 


2. 


4 00 










Did not spall at 52000 lbs. = 

per Q". 


13000 lbs. 

























BRICK FOR STREET PAVEMENTS. 



21 



TABLE No. 4. — Transverse Strength. 



SIZE IN INCHES. 



" . CO 

< ?;; H 

z " s 

2 "* " 

H K S^ 

O « "^ 







-E-a 




«5:z 




^2§ 

^ W q; 




M^ 


O aj 




R 


6590 


1501 


4580 


1222 


G500 


1801 


5050 


1310 


5G20 


1811 


7G00 


2377 


5400 


1932 


11680 


2472 


8000 


1693 


11110 


2427 


l:«20 


3089 


lllfiO 


2511 


15171. 


3288 


12460 


2657 


10870 


2329 


12000 


2496 


7020 


2292 


10250 


3525 


7840 


2650 


8320 


1959 


7850 


1820 


1 8000 


1811 


8730 


2093 


7410 


1776 


4790 


1148 


9690 


236r> 


8000 


1948 


11610 


2584 


6780 


1346 


6000 


1197 


5100 


1043 


8000 


1668 


9010 


1811 


7770 


1518 


9760 


1850 


7830 


1483 


7640 


1630 


11660 


2527 


12710 


2667 


9640 


2091 


5750 


1982 


8000 


2853 


5530 


1972 


7150 


1664 



2.25 

2.31 

2.31 

2 31 

2 125 

2.19 

2.125 

2.50 

2.50 

2.50 

2 50 

2.50 

2 44 

2.56 

2.625 

2.625 

2 25 

2 31 

2.25 

2 50 

2.50 

2,56 

2 50 

2.50 

2.50 

2 375 

2 31 

2.375 

2.75 

2.81 

2.75 

2.62 

2 55 
2.55 

3 00 
3.06 
3.00 
2.44 
2.375 
2.375 
2.06 
2.06 
2.06 
2.75 



4.19 

3 82 
3.75 
3.875 
3 625 
3.625 

3 44 
4.125 

4 125 
4,06 

3 94 
4,00 

4 125 
4 06 
4.00 
4 06 
3 50 
3,625 
3 44 
3,94 
3 94 

3 94 
3,875 
3.875 
3,875 
3.94 
4.00 

4 125 



4 25 
3 87j 
3 94 
3 75 
4,12j 
4,25 
4.18 
3.56 
3 50 
3.50 
3.75 



6.0 

6.0 
6.0 
6.0 
6 
6,0 
6.0 
6 
6,0 
6,0 
6 
6,0 
6.0 
6 
6 
6 
6.0 
6.0 
6 
6 
6 
6.0 
6,0 
6 
6 
6,0 
6,0 
6 
6,0 
6 
6.0 
6,0 
6 
6,0 
6 
6 
6 
6,0 
6,0 
6 
6,0 
6,0 
6 
6.0 



9 43 

8 82 
8 66 

8 95 
7 70 
7 94 
7,31 

10 31 
10.31 
10 15 

9 85 
10.00 I 
10 06 I 
10 39 I 
10 50 
10 66 

7 875 
8,37 
7.74 
9.85 
9.85 
10. 08 



9.69 
9. 36 
9.24 
9.79 
11.17 
11 . 24 
11.00 
10,64 
10 68 
10,83 
11.62 
12.06 
11.25 
10.06 
10,09 
9 93 
7.33 
7 21 
7,21 
10 31 



R 

■ 1444 
2040 

-2197 
2963 

-2494 

-2822 
1863 
1672 

-2299 
1195 

■1666 
1688 

-2428 

-2269 



Only one specimen broken. Broke at 
one of the lower knife edges. 



Round corners, grooved longitudinally. 

Round corners. 

Round corners. 

Round corners, grooved transversely. 

Round corners, grooved longitudinally. 

Round corners. 



Only one specimen. Round corners, 
grooved longitudinally. 



For numbers 9, 10, 11, 12, 13, 14, and 16, the dimensions are those of the estimated 
equivalent rectangular seetious. 



22 



BHICK FOH STREET PANEMENT8. 



O 



REMARKS. 


Soaked 70 hours. 
Soaked 70 hours. 

Soaked 70 hours. 

Broke and fragments lost. 
Soaked 70 hours. 

Soaked 70 hours. 

Soaked 70 hours. 

Soaked 70 hours. 

Soaked 70 hours. 




5.17 
26.59 

25 37 

10 27 

11.24 

10.89 

14.12 

17.28 




4.70 
23 93 

24.14 
9 42 

10.05 
9 80 

13 ,01 

16 31 


PER CENT 
LOST IN 
ST TEST 


000'^-..= '-l'M-Mi-(MOr-iOO^.-IO'--^i-,0^'— Or-lf-— lr-!rtr-lO 


TOTAL 
LOSS IN 
OUNCES. 


6 

5 25 

6 75 
30 75 
35 50 
10 75 

14 25 
25 
10.75 

5.50 
48 75 

15 
9.75 

10 50 
11.25 
13 75 
12.75 
13 

11 75 
1{ 75 

11 50 
10.75 

12 75 
10 50 
10.75 

13 25 
9 25. 

17 25 
18.0 
19 25 
16.50 


LOSS IN 
2d TEST. 


;:5o^^l:2l«ggogl2oSS^ooi-:''e^SSS.^'c;5oSoL2ol5oS 


IC-O O O C5 -O C<1 CC. 05 CO CC CO C3 O O <M r-( — < O C^ O CI "^ O iC !M I^ '.C «0 00 >o 






O H 


Ood-:t..0^r-irlr-.^0.-IOO^.-^r-l,-IWrH,-lr-0 r.^ V^ ^ ._ ^ ^ „ 


WEIGHT 

AT END 

OF 

1st TEST 




ORIGINAL 
WEIGHT 

IN 
OUNCES. 


116,75 
115.0 
116 
94 25 
90 
87.75 
87.75 
92 25 
91.50 
85 
80 
118 
113.75 

113 75 
112 

114 
110 
114 
112.0 
109 75 
114 
112 50 
112 25 

87 75 

88 50 
88 25 
87 75 

103 50 
103 25 

101 50 

102 50 


•Haxxai 


wfr<oc!a'~'^''5a'^^o!i!'-"-'os"^'^c;a^'^C!a^'^oiij'-"-' 


•aaawaN 


i-( r- r-H -M ■>! -M ri CO CO CO CO "* >* ■* TT lO >^ O l-O -O O :» O l^ t- t- r- 00 CO OC OO 



BRICK FOR STREET PAVEMENTS'. 



23 







>^ . o 






1 s s 






t. ^ T* 






SJ a be 






> 3 r/- 






2 o £ 






a ^ <u 






S "^ S 






2^ <» o 






■^ . w « 


m 


-s^ 


s fi 1 1 |1 


a, 


|5? 


M 05 tn OT M ^ 


< 


TxS 


Ed 








^.2; ..iit- .fcj . i-, .»- .oc 




t s«^ 


O-^cS O-cS'^ O::^^ o-"^ Or^ o^,^ a> 


i 


O 3=0 


■ 


g oS o ^50 go go g C -5 


. 


o - 


Si - "^ - ^H t-lnt-i Ql 




^ >-? 


'O-C'ac^'c «'C .-a.-oflp. 




<1> -<!• 


(uoo <y Or- ajc-J oco oTti a> <u m 


, 


Jd, <:^^ 


^, •-'^ ^,^— Zd,-- ^.'-' ,t«i,'-' ^.-ii -. 

cS-vO cj-O- 13-^- =S-X si'X c3-0 2 


1 


ce- -o 




o o >- 


oCt^^fc-Oo^O^O^ c^^ 


j 


M ^P3 


ro J^aq (» pq;?; r^ J?; ^ ;^. M ;?; ;» pq O 


1 iH 


^ 


— , 


^Tf 


ST-^ o"-^ «-. -rf. t- f-,-- 1^ 


CiO 


•^ .-1 ^10 c-i Ol 


\ %ll 


00 c^ 


CO CO •>\T-i "C; irr TTi 00 




£i^ £L"^ (N ^ ^ ^ ^ 


E-" ',■• 


















1 ^ti 


cS'o 


§^ i'f-^ 2 r^ ^ ■:^ E^ 

■M 'M ^0 'O -^ 5C OS 


--■zt 


.-iCO 
00 .-i 


|2S 


l-HrH 


-Mr-, -M T-( IM I-t ,-( 






E>=g 


^ ,v ,. ^ ^ ,. ^ 1 




^' ^' ^ ^' ^' ^ 


Sis 




<M 


O O lO "C 


l-t-» 1- 00 Ci 5^ Tj<-MC^0C(NcOt^cOcOI^l- ri I---: — bOOO 


= OH 


o^o o 


000 r-. 00 rH,-(Ol-HOOOOOOOOr-,r- SCC-HO 


w.j!c 




C'O 


a- t— 






t^i 

< ^ u 


iC i.C lO 


Sl2ooSgo53^1gS^^gl5ooS;3§goS'^3ooog 


C^l O l^ l^ o 


F- a2 ii 

5 X :z; 


rH lO O CO I^ 


S^Si|SSgd-J^S5Si§SS?SSS^^2S=^;;'^'«^^-*^ 




-! O 






S^' 


^ 


• 


lOicio^oo loiciftm o lO'OOi.sift ooiftioift.ft lo o ■'mc 1 


05 H 


CN o^1^4 o| lo 


.rDOOCMJ>c~.l-O.COl-l^.O<M<NOO^l-l-l^I^Ol- Ml- 


OcoOeotccsi--r-rrC5ao:«-^'-'iOc3i---*'-<ooaor--^-^'Mooocc->!(< r)< i^r^ 1 


9q 


^^^■,^_ 


t-lr-liO I^'Mi-liHCMMCOC0i-li-n-(*Ji-lr-i r-l r-( 










— , r— , 


ift; i-O 


i- .C i^ lO iC "O >C iC i.t 10 lO lO 10 iC iC lO 


oii^o o 


i-ir^Ol-C^liO l- .0 0<M<MOiOl--l-:^irt(Mi>(MOC^l-~uo.Ql-i<l 


1^ .-J iC o 


cr, 'M 1-- '^ .0 — O^COtT ^1 CO -*Tt<Ot^iC COO (M-M OX Cicios 


H 


C5C1CJ OO 


C5Ci»o^Si-j c^ r-j-_;C3Cioo> — -^j-jooomoi^i-^ocbo 






5s 


lO o o 


lOiC lO lO uo loooo \rt Oi;t 'ftoioiOic>oo"oLOuo 


_ w 


oi^^s >o 


t^l-O I- C-I C^l l-urju-5uOOiCl-Ol^l-l^l-!Nl-iMl-Si-Ol-l- 


M =^ 


i-lrHO O 


OOtH d M r-( OOrHi-lr-lr-IOr-lOOOOOOr-lOCOM'oO 


ss 




0-1 


IGHT 
END 
OP 
TEST . 


O iC o 


ifto uo 10 OiT. >-r>- .oiooi — . 


LOOI-I ift 


C^iCO 1^ t^ COOOiCi^=:i-l-OOir:Ot^C<1.00000 


J-ii^l- o 


oo~. Tt< i;? CO 01 i-ooc'^ T — — ~i rt ri i~ := ■O'MiOiOCO'^r^.-i 




ooo o 


000 CI ^ onMC-1 01 ri Ti :t c- :-: rt ooooi^i--..-:-i-i-(M 


_ 1 


2 aa: o 


o.c.^ 


iC >.0! ^ ^ iCO OOO.T iT.COi-.Oi- lOOOiT 1(0 lO 


m i^ i^ o 


cj t- I- lO 'C in. >;5 CM I- 1^ .ft t- I- c^ c^j ic lo m lO 1^ 1^ 




°M°. o 


S2S 8 ^. 5 {:5?ifl!^S?,?g?2S?^S'a'a8SS S I^?5 


1 


•tiaxxai 


^WHUH ^ 


■Z^^ ^ C3 ^ -^'-^OS^^->5S"^^-H^^OK ^ "^ 


•HaawnK 


C-. Si -. C-. 


000 ^ — ^»-<MM(M(NcocrcocO'*<-^T}<<*ioio lo mo 







24 



BRICK FOK STREET PAVEMENTS. 



TABLE No. 6. — Comparative Rank. 



Rank. 



First 

Second 

Third 

Fourth . . . . 

Fifth 

Sixth 

Seventh... . 
Eighth .... 

Ninth 

Tenth 

Eleventh . . 
Twelfth . . . 
Thirteenth 
Fourteenth 
Fifteenth.. 
Sixteenth . . . 



o 

O P 

go 



9 
16 
11 
12 

8 

4 
14 

() 

9 






1 &15 

13 

10 

7 

6 

12 

3 

14 

16 

8 

11 

9 

5 

4 

9 



OQ ^ 



16 

1 

15 

14 

4 

7 

10 

5 

6 

13 

8 

9 

2 

3 

11 

9 



K EH 



6 
14 
10 
15 

4 

3 

8 
13 

9 
12 
16 

1 I 

2 
11 



o <J 



05 1— I 



1 
4 

16 
6 

14 



15 

13 
8 
9 

11 

10 
•> 

12 

9 






1 

16 
3 

7 

5-10 & 15 

12 

9 

11 

4&6 

2 

14 

13 



BRICK FOR STREET PAVEMENTS. 



9r. 



TABLE No. 7~Loss of Brick tn Terms of Granite. 



Specimen Num- 


First Rattler 


Second Rattler 


Entire Rattler 


ber, 


Test. 


Test. 


Test. 


1 


1.0 


1.0 


1.0 


2 


8.1 


5.0 


5.1 


3 


3.8 


5.1 


4.9 


4 


1.9 


2.0 


2.0 


5 


3.0 


2.1 


2.2 


6 


2.0 


2.1 


2.1 


7 


3.0 


2.7 


2.7 


8 


2.6 


3.4 


3.3 


9 


2.0 


3.8 


3.7 


10 


1.7 


4.8 


4.5 


11 


2.1 


4.6 


4.3 


12 


2.5 


5.3 


5.0 


13 


1.4 


3.1 


2.9 


14 


1.4 


■ 
2.2 


2.1 


15 


20.0 


1.4 


2.9 


16 


K4 


2.0 


2.0 



26 



BRICK FOR STREET PAVEMENTS.. 



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brick for street pavements. 27 

Description of the Tables. 

Table IN'o. 1 requires but little description. It shows the 
essential cliemieal ingredients of the different varieties of 
bricks tested as obtained from a single analysis of each kind. 
Generally the sample was taken from the crushed cubes, but 
where we failed to crush them pieces were taken from other 
broken specimens, using the common mortar and pestle for 
pulverizing. Could a larger quantity of each variety have 
been ground and used in sampling, or a greater number of 
analyses have been made, a more accurate average determi- 
nation would have been obtained, but the time and expense 
required for such work is so great that it was deemed pru- 
dent to limit our investigation to the single analysis. It is 
evident that an inquiry into the nature of the material of 
which the bricks are composed is the proper basis for a study 
of the whole matter, and should next be followed by a scru- 
tiny of the methods of combination. These searches should 
then be followed by tests of the goods produced. Without 
proper clay no good result can be expected, and with suita- 
ble materials improperly combined failure is sure to follow. 
From the first cause I would cite numbers 3 and 15, as not 
meeting the requirements ; from the second, numbers 2, 11, 
and 12 are conspicuous examples. 

Could our analyses have been made from the clays used, 
we should have been working to better advantage ; but that 
Avas not practicable for us under the circumstances. In or- 
der to show that the results obtained are entitled to credence, 
I have compiled Table N'o. 8 from the sources named in its 
description, which shows that the work done has been care- 
fully performed. 

Table No. 2, is a detailed statement of the results of the 
investigations to determine ratios of absorption and specific 
gravities. The method of performing the work has been 
described. N"umbering the cokimns from left to right, the 



28 BRICK FOR STREET PAVEMENTS. 

first is the specimen number ; the second is the weight in 
grammes of the cubes lettered "A" after being dried; the 
third is their weight after soaking twelve hours in water; 
the fourth is the excess of the third over the second, which 
is obviously the weight of moisture absorbed ; the fifth is 
the quotient (multiplied by one hundred) of the fourth di- 
vided by the second, or the percentage of absorption ; the. 
sixth is the weight of the cube in water; and the seventh is 
the specific gravity. This was determined by the formula : 

W 

Specific gravity :== 

\\v ^// 

In which W equals weight before immerson, W equals 
weight after immersion, and W equals weight in water. 
The remainder of the table details similar experiments witb 
whole bricks, using a less accurate means of determining 
weights, column eight giving the letters designating the mark- 
ing of specimens of the several numbers (it will be noted that 
these bricks appear again in The Rattler Test — Table ^o. 5); 
column nine giving the weight in ounces before inmiersion ; 
column ten, the weight after soaking seventy hours in wa- 
ter ; column eleven is the excess of ten over nine, being the 
weight of water absorbed ; column twelve is again the per- 
centage, or the quotient multiplied by one hundred of eleven 
divided by nine ; and column thirteen is the mean of the 
two results from specimens of the same number in column 
twelve. 

The latter test is not one of great accuracy, and the 
tabulated results can not show all of the influences which 
should be taken into consideration. For example, numbers 
three and fifteen were smooth, clean bricks when put in water, 
but when they were taken out their surfaces were defaced 
by numerous indentations caused by the dissolution of the 



BRICK FOR STREET PAVEMENTS. 29 

contained material. This loss lessens the apparent amount 
of absorption, and unless provision is made for determining 
it in each case it can not be measured. It, however, re- 
veals a serious defect, Avhich should not be overlooked. 
Where nothing of this kind is a[)paront tlie test is a very 
practical one, and can be repeated at pleasure with the ordi- 
nary counter-scale and but little trouble. It furnishes a very 
fair test of the absorbing qualities of the material. 

Table I^o. 3 sets out in detail the results of the work 
done to ascertain the crushing strength of the materials 
tested. The method of preparing the specimens having al- 
ready been described, it is not considered necessary to set 
forth in further detail the manner of arrivins^ at the results 
here tabulated, as that will be evident from a mere inspec- 
tion of the table. A glance at the results obtained shows 
us that we are not dealing with the substance ordinarily 
known as brick. 

In Table E'o. 4 is given the work done to ascertain the 
transverse strength of the material. The Riehle testing ma- 
chine of Messrs. Otten & Westenhoff was used for this 
purpose. Three whole bricks or blocks, lettered D, E, and F, 
of each variety were broken, excepting numbers one and 
sixteen, of which but one each could conveniently be had. 
The bricks were supported on knife edges six inches apart, 
and the load w^as applied by another knife edge brought to 
bear midway between, and parallel to, the other two; each 
point of bearing being protected from direct abrasion by 
two or three thicknesses of blotting paper. 

The modulus of rupture w^as computed by the ordinary 

formula: 

3 w I 
R-= 

3 6 d' 

in which W represents the breaking w^eight in pounds, h, (/, 



30 BRICK FOR STREET PAVEMENTS. 

and U the breadth, depth, and length, respectively, all in 
inches, and E, the modulus of rupture in pounds. If the 
span I be measured in feet, while b and d are measured in 
inches, the formula becomes 

K=18 



hd' 



Hence, the modulus of rupture is stated by Prof. Rankine to 
be " Eighteen times the load required to break a bar of one 
inch square, separated at two points, one foot apart, and 
loaded in the middle between the points of support." While 
this is the ordinary formula used in the text-books, and 
identical with that adopted by Prof. Baker in his recent 
publication upon "• The Durability of Brick Pavements," it 
should not be confounded with that commonly employed 
for determining the transverse strength of material, which is 



/ W 



4tt d 



In which R represents the coefficient of transverse rupture ; 
W the breaking weight; a the sectional area; d the depth; 
I the length, all in inches. Results obtained by the latter 
formula will be found to be about \ of those derived from 
the one first stated. 

In the table, the first column on the left gives the speci- 
men numbers; the second, the letters by which they were 
designated; the third column is the breadth or thickness; 
the fourth, the vertical depth; the fifth, the length between 
supports, all of these dimensions being in inches. The sixth 
column is the product of the third by the fourth, being the 
area in square inches. The seventh is the weight in pounds 
at which the specimen was broken ; the pressure being ex- 
erted by the continuous working of the pump without shock 



BRICK FOR STREET PAVEMENTS. 31 

until rupture was produced. The eighth column is the mod- 
ulus of rupture calculated by the formula first above given. 
This formula is stated in Professor Baker's pamphlet, page 
5, in the following form : 

2 h d^ 



W: 



3Z 



The letters having the same significance as above given, but 
a moment's inspection shows this expression to be identical 
with that used in calculating the table. The ninth column 
shows the averages of the three results given in column 
eight for specimens of the same kind or number. 

Table 'No. 5 is a detailed statement of '' The Rattler 
Test," or the effort to measure the effect of abrasion and im- 
pact upon the specimens submitted. The method of con- 
ducting the test has already been briefly outlined. Tabulat- 
ing the result has been a tedious process, but it has been 
done with much care, and is believed to clearly show the re- 
sults obtained in such a manner that the value of the test 
can be judged from a correct basis. All the weights were 
carefully repeated, and, if errors have been made in the cal- 
culations, all the work is given in detail, so that corrections 
can be made by inquiring minds if incorrect results are 
found in any of the columns. 

Counting from the left, the first column gives the speci- 
men number ; the second, its letter (those marked G- and H 
having just come from their bath in the absorption test — 
Table 'No. 2) ; the third, its weight in ounces when placed in 
the rattler; the fourth, its weight after the first thousand 
revolutions, or at the end of the first test. There was an in- 
terval of nearly forty-eight hours between the first and sec- 
ond rattler tests, and the weighing was repeated before 
placing the specimens the second time in the cleaner, but the 



32 BRICK FOR STREET PAVEMENTS. 

loss in weight by evaporation from the saturated bricks did 
not appear to be a measurable quantity by the instrument 
used, which was a new Fairbank counter scale, weighing to 
quarter ounces. The fifth column is the excess in the 
weights given in the third over those in the fourth, or the 
loss in ounces of each specimen in the first test. The sixth 
column gives the weight of each specimen at the end of the 
second or final test. In a few cases, there was uncertainty 
about the identity of some specimens, as the marks had been 
so defaced, but in all instances the varieties could readily be 
distinguished. Where figures are inclosed in parentheses, 
they include the weights of the pieces Avhich had been broken 
off and were of sufiicient size to be saved and weighed. 
The seventh column is the excess of the weights given in the 
fourth over those in the sixth, being the loss in the second 
test. The eighth is the sum of the seventh and fifth, or the 
difference of the third and sixth, being the total loss in both 
tests. The ninth is the quotient, multiplied by 100, of the 
fifth divided by the third, or the percentage, to the nearest 
tenth. The tenth column is the percentage of loss in the 
second test, and is obtained by dividing one hundred times 
the sum of the losses for specimens of the same number, 
taken from column seven, by the sum of the weights of 
specimens of that number, taken from column four. The 
eleventh column is calculated in the same manner, using the 
sum of the weights for each variety or number as given in 
column eight, and the sum of the weights of the same variety 
in column three. 

Table Xo. 6 is compiled from the results set out in the 
preceding Hve tables; the several numbers being rated with 
each other in the order in which they have withstood the 
various tests to which they have been subjected. It shows 
some rather unexpected results and is worthy of very care- 



BRICK FOR STREET PAVEMENT:?. 33 

fill study. The rank is by averaging all the tests of each 
kind for each number or variety in each test. Thus, in the 
absorption tests, those numbers showing a less average per- 
centage of absorption are ranked higher than those showing 
a greater percentage. In crushing strength, those showing 
a higher power of resistance rank above those showing a 
less endurance. In this test, unfortunately, our machine 
had not the power to enable us to properly classify the better 
grades of material tested, but the rank so given is strictly in 
accordance with the results of the work. It is not thought 
that Xo. 16 is absolutely a stronger material than granite, 
but one of the granite cubes was slightly spalled at a lower 
pressure than was exerted when the Xo. 16 cube was spalled, 
but none of the cubes of either number were crushed, hence 
the actual endurance of the material remained undetermined. 
In transverse strength, the numbers having a greater average 
modulus of rupture are ranked above those having a less, 
which correctly classifies the material as to its tenacity under 
stress as it was applied in making tests, but furnishes but a 
poor criterion by which to judge of the quality of brittleness 
under percussion or shocks. Under abrasion and impact, 
the numbers are ranked according to the percentages of loss 
in the second rattler test; those suffering a less loss being 
ranked higher than those suffering a greater one. 

Table No. 7 is deduced from the percentages given in 
table No. 5, the loss of the granite being taken as one. The 
left hand column gives the specimen number; the second 
column its ratio of loss in the first test; the third column its 
ratio of loss in the second test, and the fourth column its 
total ratio of loss in both tests. For purposes of comparison 
it is recommended that the figures in the third column l)e 
used. It will be seen that the best bricks under the most 
3 



o4 BRICK FOR STREET PAVEMENTS. 

favorable conditions siiifer about doable the loss which the 
granite does. 

Table ^o. 8. This table has been compiled for the pur- 
pose of comparing the work of other investigations with 
that herein described. The first analysis given is a Stour- 
bridge iire-clay used exclusively for the manufacture of glass 
house pots and furnace linings. It is a coal measure clay 
and probably contained traces of lime and magnesia, but no 
mention of such ingredients is found in Mr. Wills's analysis. 
The second analysis by the same chemist is of a clay from a 
like source, but in this case he has determined the percent- 
age of lime contained, which is very small indeed. These 
clays are mined and used because of their heat resisting 
qualities, and are principally valuable because at white heat 
they do not readily vitrify, but retain their form and tex- 
ture. The third analysis is of a i!^ew"castle lire-clay, by Mr. 
Taylor, the product being less remarkable for resisting heat 
than wear. It is to be observed that this clay contains in- 
gredients which at a white heat will unite or vitrify, but 
would hardly be likely to become fluid or even sulKciently 
plastic to greatly change in form. It is quite similar to our 
I^os. 4, 8, and 14, except that it contains much less iron. Tlie 
fourth analysis, from Percy's Metallurgy, is of the Glasgow 
iire-clay, adapted to a variety of metallurgical uses, is an 
average of many determinations in which, unfortunately for 
our purposes, the percentage of alkalies is not given. With 
this exception it gives the characteristic ingredients of the 
coal measure fire-clays. The fifth analysis is of the white 
clay of the tertiary formation in Dorset, by Professor Way. 
It is used for the manufacture of fire-brick and could prop- 
erly be termed a modified fire-clay. The analysis gives the 
alkalies as '^ alkalies and alkaline earth," and the lime as a 
sulphate. This clay contracts very greatly in the process of 



BRICK FOR STREET PAVEMENTS. 6b 

drying and burning, to counteract whicli tendency it is cus- 
tomary to incorporate with it tine sand and ground burnt 
chiy. Kumber six is the Beacon Hill chxy from the Lower 
Bagshot Beds, which withstands the high temperatures of 
furnace linings without much tendency toward vitrification, 
but decrepitates or is worn away by passing currents. The 
seventh analysis is taken from a recent publication by C. P. 
Chase, on "Brick Pavements," and gives the composition of 
the clay used in the manufacture of the Hale paving brick. 
Mr. Chase gives the moisture at 212 degrees as 2.08, and 
combined water as 5.16, but does not determine the alkalies 
present, if any were contained in his sample. If the writer 
understands what is meant by the Hale paving brick, this 
should correspond with our 'No. 2, Mr. Chase's analysis hav- 
ing been made from the clay and ours from the brick, but 
the resemblance is not very close. The eighth analysis is 
copied from the same source as the preceding one. The ma- 
terial in its natural position more nearly resembles a fine- 
grained sandstone than a bed of fire-clay, but it pulverizes 
readily on exposure to the atmosphere, and its composition 
and position have given it its name. From it is manufac- 
tured the Hay den block, which is, in reality, a tile used for 
paving streets. No sample of this material was furnished 
for testing, but it has been used extensively as a paver, and 
in some localities is deservedly popular. When properly 
burned and annealed it presents a homogeneous, compact 
texture, and has great hardness without brittleness. Many 
persons would say that the material was " perfectly vitrified," 
but that expression needs specific explanation to be at all in- 
telligible. The ninth, tenth, and twelfth analyses are copied 
from the same author, who also gives the specitic gravity, 
crushing strength, and percentage of absorption of the bricks 
manufactured from these clays. While he classes them 



36 BRICK FOR STREET PAVEMENTS. 

among " our best paving brick," he giv^es no statistics show- 
ing their enduring qualities in actual use. They would more 
nearly coincide with our No. S than any other sample tested^ 
although they might not resemble it in color. The writer 
would not regard ISTo. 10 as a very promising composition, 
but all of these clays can be melted or vitrified very readily 
so as to present a compact texture that will not absorb moist- 
ure in any considerable amount. The eleventh analysis is 
from the same author of a clay used by the American Brick 
and Tile Company, of Phillipsburg, New Jersey. This com- 
position is also said to contain sulphur 0.89, and phosphoric 
acid 0.13. No further information is given regarding the 
]>roduct except that the crushing strength averages from 
V,000 to 7,500 pounds per square inch. The thirteenth and 
fourteenth analyses Avere made by Otto Wuth, of Pittsburg, 
the first being of the Porter fire-brick and the second of the 
ground clay from which such bricks are manufactured. 
These compositions, it will be noticed, are quite similar, ex- 
cept that the brick has had the moisture driven ofl:' in burn- 
ing. They closely resemble our No. 14, except that we find 
a much higher percentage of the alkalies, and herein lies 
the marked distinction between the fire-clay brick, w^hich is 
suitable for furnace lining, and the one adapted to use in 
iitreet paving. 

The Chemfstry of Brick Manufacttjring. 

The alkalies of potash in the clays is a residuum of de- 
cayed organic matter. It is an active fluxing agent, and in 
the process of burning, or so-called vitrification, causes an 
amalgamation of the iron and silica components w^hich imparts 
a metallic tone or ring to the brick when struck. When 
aided by finely pulverized lime or magnesia m the presence 
of a large percentage of iron, a pale double silicate of lime 



BRICK FOR STREET PAVEMENTS. 37 

and iron is formed, imparting a butt' tint to cla^^s that would 
otherwise burn red. Ln the tire-clays less than half of one 
per cent of potash or alkali produces no noticeable result, and 
the product has good heat resisting qualities, but when from 
one to three per cent of this ingredient is found in the clay 
and it contains from four to eight per cent of iron, which it 
generally does, with perceptible quantities of lime and mag- 
nesia at a high temperature (usuall}^ a white heat), these flux- 
ing components form vitreous combinations with the silica, 
producing a brick quite useless for resisting heat, but when 
the texture is uniform throughout, and it is allowed to cool 
gradually, without coming in contact with cold air until be- 
low the temperature ot" boiling water; or, in other words, is 
properly annealed, you have the so-called vitrified brick, 
which absorbs about two per cent or less of moisture, and 
has great strength to resist crushing or abrasion. This 
product may be used quite fearlessly for street paving. 

With the plastic clays or shales the melting or vitrifica- 
tion occurs at a lower temperature, and, owing to the fact 
that the ingredients are seldom uniformly mingled, there is 
greater danger of melting the bricks together in the kiln, or 
of leaving many of them without vitrification. To render 
them apparentl}' impervious to moisture, many manufactur- 
ers have adopted the plan of glazing them with salt, which 
may be beneficial in some respects, but is objectionable in 
others. These clays usually contract to a greater extent in 
the process of drying and burning than the fire-clays do, 
and hence are more liable to be warped from their proper 
form, or show injurious fire cracks. But no clay can be 
made into a good street paving brick, unless the process of 
firing or burning be continuously progressive and compara- 
tively slow to the maximum temperature, and the cooling 
down be gradual and continuous. This can not be done in 



38 BlUCK FOR STREET PAVEMENTS. 

the ordinary clamp-kiln. A broken brick showing varieties 
of texture or color is a certain indication of defective com- 
bination or burning, and the fault is fully as liable to be in 
the burning as elsewhere. Uniformity in the product of the 
kiln is a necessary condition to the successful manufacture 
of clay of any kind into proper form to be used for street 
paving; and only with such clays, and such appliances as 
will enable the manufacturer to attain this result, can he 
reasonably hope to achieve success. 

Discussion of the Tests. 

With the information now before us, what brick shall be 
selected? If the tests were of uniform value the numbers 
should range in horizontal lines across Table J^o. 6, the best 
material at the top and the poorest at the bottom ; but we do 
not obtain such results. There are other considerations that 
can not appear in the tables, ^earl}^ 50,000 square yards of 
surface are to be paved, and the availability must be consid- 
ered. That which can be promptly furnished in large 
quantities should be chosen, even though an article may be 
inanufactui'ed which is better in some respects, but unattain- 
able without great delay. But people wdiose ojDinions are 
entitled to great respect will honestly differ as to the relative 
value of the several tests. For example. Prof. Baker, in his 
pamphlet on " Brick Pavements," expresses the opinion de- 
cidedly that, "As a test of the quality of brick or stone, the 
crushing strength is practically Avorthless." (Baker on Brick 
Pavements, p. 8.) He demonstrates in a concise manner that 
the weight on the wheel of a loaded vehicle is not likelj^ to 
crush a brick, even though it be soft. Yet the jirofession gen- 
erally have considered, and probably will continue to regard it 
as essential, that the constructing engineer should be informed 
as to the crushing strength of the materials which he uses, 



BRICK FOR STREET PAVEMENTS. 39 

and that, in connection with other information, it is an 
efficient aid in determining the relative value of different 
building materials. However, it is only one of the elements 
to be considered. For example, the crushing strength of cast 
iron, is about twice that of wrought iron, and of steel more than 
twice that of cast iron, but this does not make cast iron worth 
twice, nor steel four times as much as Avrought iron for use 
under compressive stress. In fact, the best practice adopts 
wrought iron in preference to either of the others for many po- 
sitions, but a knowledge of the sustaining power of the mate- 
rial is, and must be, essential to the designer. A study of the 
preceding tables shows that those specimens having a high 
crushing strength also rank well in the test for abrasions 
and impact, and it is reasonable to assume that the power to 
sustain great weight without crushing would be necessary to 
the durability of a block placed in a roadway, and subjected 
to the attrition and grinding due to that position. It is true 
that many experiments or tests are conducted in such a 
manner, and the results given so incoherently, that they are 
of little value, but where the work is carefully done, and 
the record clearly set out, so that knowledge of the com- 
parative strength of different substances can be gained from 
it, information regarding the crushing strength of any pav- 
ing material to be used in the form of blocks, will be sought 
and esteemed as of great merit in determining the value of 
such material. A recent circular from the State of 'New 
York has been placed in the hands of the writer, in which 
it is stated over a name preceding the title of civil engineer, 
that the " average resistance to crushing per square inch is 44,- 
000 pounds " for a certain description of brick which had been 
tested by him. !N'ow, if that civil engineer had informed the 
public at large by what steps he had arrived at that remarkable 
conclusion, he w^ould have conferred a benefit upon his fellow 



40 BRICK FOR STREET PAVEMENTS. 

men. The same circular contains further information as fol- 
lows: " Under an abrasive test equal to a traffic tonnage of 
100,000 tons per inch of width, the loss was nine-sixteenths 
of an incli, or six and one-fourth per cent of the depth ; thus 
under a daily traffic of 100 tons per foot ol width of street, 
this brick would have a traffic life of twenty-eight years." 
That conclusion appears to be quite definite and satisfactory,, 
but there are ignorant people at large who know neither 
just what that abrasive test might be, nor by what process 
of reasoning such a result is reached. Some people might 
think that a daily traffic of 100 tons per foot of width for a 
period of twenty-eight years would not be equal to a traffic 
tonnage of 100,000 tons per inch of width, and thus conclude 
that, if the first premise is correct, such a pavement would, 
be good for at least two or three centuries; even upon the 
assumption that when it was half worn out the abutting 
owners might want it renewed for a change. 

The work done at this time for determining crushing 
strength is very incomplete, owing to the limited capacity 
of the machine, but it is believed to be accurate as far as it 
extends, and enables us to properly classify the specimens 
not having a resisting capacity exceeding 13,000 pounds per 
square inch. 

The Absorption Tests. 

For this class of paving material, a low ratio of absorp- 
tion is held by many to be a most essential condition, and 
therefore that this test is of the greatest importance. In our 
work this theory has not been accepted. Of all the speci- 
mens tested there is but one (No. 2) which should be rejected 
because of its excessive absorption alone, were all other 
characteristics satisfactory. Manufacturers have been told 
so frequently that a non -absorbent product is a necessary 
condition for marketable goods, it is so easy for them to- 



IJKK'K FOR STRP:ET PAVEMENTS. 41 

l)riiig the rate down to two or thi-ee per cent, and the te^^t 
can be so readily made, that hut few street paving bricks are 
in the market which absorb moisture as freely as any of the 
stone blocks except granite. It is probably unfortunate that 
no variety of stone, other than Georgia granite, was included 
in the tests made, but sufficient experiments have been made 
with the various building stones to show that when the ]>er- 
centage of absorption is three or less, and the material is 
not laminated, they are neither perceptibly softened, nor 
made susceptible of destruction hy climatic influences. Me- 
dina sandstone absorbs from two to four per cent of moist- 
ure. Oolitic limestone absorbs from three to five per cent, 
yet no one asserts that either of these stones is softened or 
aftected detrimentally on this account, and the first is a stand- 
ard paving stone. Again, of the specimens crushed or 
subjected to abrasion, there is no indication, unless it be Xo. 
2, in the Rattler test, that any one was weakened by its pre- 
vious soaking. Therefore, while it is undoubtedly true that 
a strictly non-absorbent material is the best, yet, among the 
paving bricks having percentages of absorption lower than 
three, while the advantage of an exceedingly low rate should 
not be ignored, other features may be considered. For in- 
stance, jN'o. 13 is shown to absorb less moisture than granite, 
and where it is not to be subjected to an excessive traffic, 
should on this account be favorably considered, but its en- 
durance under severe tests appears to be exceeded by some 
of the other varieties. 

Transverse Strength. 

The manner in which the transverse strength of the 
specimens submitted was determined has been described and 
tabulated, but in doing the work much information was 
gained that could not be written out. An unexpected de- 



42 BKICK FOR fcTREET PAVEMENTS. 

^ree of strength Avas exhibited hy ii niajority of tlie speci- 
mens. "While tliis test shows tlie tenacity of tlie material 
under a stress continually increasing- to the point of rupture, 
it gives but little information about the ability of the same 
substance to withstand the effect of blows or shocks. The 
Lehavior of the bricks at the instant of rupture is instruct- 
ive. Some of those which carried the greatest weights were 
much shattered. One of the number fives broke into three 
triangular pieces of nearly equal size. ^N'early every speci- 
men which exhibited the characteristic vitrified appearance, 
threw off flint-like s})alls, and presented an irregular fract- 
ure. Those specimens which in other tests manifested the 
greatest endurance were usually parted by a clean fracture 
almost at I'ight angles wnth the brick, directly beneath the 
central bearing, like the granite; while those having interior 
defects of any kind would separate at any point between the 
outer bearings. This test, therefore, is of much value to the 
experimenter, but the tabulated result is not a sure indica- 
tion of the value of the material for street paving purposes. 

Abrasion and Impact. 

The manner of conducting this work has been so fully 
•described, and the results set out in such detail in Tables 5 
iind 7, that further comment is hardly necessary, yet it is 
plain that it presents no condition at all similar to that 
which obtains in actual service. The bricks are loose and 
battered upon all surfaces, whereas in the pavement they 
are held firmly in place and subjected to abrasion upon one 
side only. But in this case they were all subjected to the 
same treatment, and their losses should give a fair measure 
of their relative powers of resistance. ** The Rattler Test" 
has been frequently repeated by various parties, and a prac- 
tice is coming in vogue of assuming that a half hour or an 



BRICK FOR STREET PAVEMENTS. 43 

hour in the rattler is equivalent to a year's wear in the pave- 
ment under a given amount of traffic, and from this assump- 
tion the prohahle life of the hrick in actual use in the street 
is calculated. By a somewhat similar course of reasoning, 
although the premises are more fully and fairly detailed, 
Professor Baker has calculated Table No. 7, given on pages 
32 and 33 of his pamphlet on Brick Pavements, in which 
the life of a pavement made of each of the varieties of brick 
Avhich he tested, is given in certain streets of ten of the 
principal cities of this country. The daily traffic tonnage is 
taken from Captain Greene's statistics, and the results as 
tabulated are remarkable. His poorest brick would last four 
years on Broadway, ^N'ew ^ork, and one hundred and sixty- 
five years on Olive street, St. Louis; while his best brick 
would last thirty-eight years on Broadway, and fifteen hun- 
dred and twenty years on Olive street. The writer does not 
dispute such conclusions, but has no facts from which simi- 
lar inferences can be drawn. 

Statistics of Traffic and Durabililty of Pavements. 

Data regarding the traffic tonnage, and the efi:ect of such 
wear on street pavements and highways, has not been col- 
lected and preserved in this country in such form as to be 
available for ready reference. A few years since, Captain F. 
V. Greene prepared a paper, "An Account of Some Observa- 
tions of Street Traffic," which was published in Volume 15 
of the transactions of The American Society of Civil Engi- 
neers. The observations were made by employes of The 
Barber Asphalt Paving Company, under Captain Greene's 
directions, during the months of October and November, 
1885, in the ten large cities in which that company had 
offices and works. "The agent in each city was instructed 
to select the three streets in that city paved with stone, 



44 BRICK FOR STREET PAVEMKNTS. 

asphalt, and wood (if any existed), which, by common re- 
port, had the heaviest traffic in the class of pavement used 
on that street. The record was in every case made on six 
consecutive days (Sundays omitted), at the same place, and 
it was continuous from 7 a. m. to 7 p. m., except when dark- 
ness prevented. No addition was made for this omission ; 
no record was kept during the night, and no addition wa^ 
made as an estimate of night traffic." '-The traffic is di- 
vided into three classes, light weight (less than one ton)^ 
medium weight (between one and three tons), and heavy 
weight (more than three tons). 

The Captain says : " I have discarded the weight of the 
horses altogether, not because they do not constitute a factor 
in the wear of the pavement, but because they Avere dis- 
carded in the English reports, and I desired, as far as possi- 
ble, to make comparisons with them." . . . "To obtain 
the tonnage, I estimated the light weight vehicles to average 
one-half ton each (including their loads), the medium weight 
two tons, and the heavy weight four tons." 

r l-horse carriages, empty or loaded. 

Light weight included -{ l-horse wagons, empty or light-loaded. 

i l-horse carts, empty. 

{l-horse wagons, heavy-loaded, 
l-horse carts, loaded. 
2-horse wagons, empty or light-loaded. 

Tj / Wagons or trucks drawn by two or more 

Heavy weight included... | \^^^^^^ ^^^ ^^^^^^ ^^^^/^ 

" The average tonnage per vehicle ranges from 0.68 on 
Fifth avenue (New York) to 2.08 on a portion of Wabash 
avenue (Chicago). On Fifth avenue, 91 per cent of all the 
vehicles weigh less than one ton, while on Wabash avenue, 
only 25 per cent of them have so little weight. The general 
average for all the cities is as follows: Less than one ton^ 
67 per cent ; between one and three tons, 26 per cent ; more- 



BRICK FOR STREET PAVEMENTS. 45 

tlian 'three tons, 7 percent. The average tonnage per foot 
in each city, so far as here observed, varies from 151 in New 
^York to 30 in Buffalo, and the general average is 77. For 
:all the cities in the table, the average daily tonnage per foot 
^of width is 77, and varies from 273 tons on Broadway to 7 
"tons on a granite street in St. Louis. The average weight 
.per veliicle is, for all the cities, 1.15 tons. The average 
^width of street between curbs is 44 feet." 

This is believed to be the first carefully prepared census 
of travel made public in this country, and it was published 
by an officer of an asphalt paving company. It is fair to 
presume that one object in view was to show the durability 
•of that kind of pavement under heavy traffic. Since its 
publication, a few annual reports have contained statistics 
upon the subject, and the investigation has been greatly ex- 
tended by the diffi^rent asphalt paving companies. Obvi- 
ously, information of this kind should be officially compiled 
by municipal officers upon a uniform system throughout the 
country and its scope materially extended. The effect or 
wear upon the roadway of an observed traffic tonnage should 
be given, which has not been done except in a few of the 
English reports, and there mainly in cost of maintenance 
or repairs. Reports from Washington have given some data 
as to the cost of maintenance of certain pavements, and the 
English reports are usually quite explicit upon this point; 
but it would greatly benefit all municipal corporations in this 
country, were each to keep a record of the kind of street im- 
provements made, their manner and cost of construction; 
their durability and expense of maintenance, under a traffic, 
the volume of which could be noted with reasonable accu- 
racy, at but trifling expense. The omission of the horses 
from the traffic census is clearly a fault, as we know that 
they assist largely in wearing the roadway. For example. 



4G BRICK FOR STREET PAVEMENTS. 

between the rails of street car tracks upon lines operated by 
horses or mules, the wear of the })avenient is due almost ex- 
clusively to this cause, and it is known to be very great. 
The tonnage of vehicles, as estimated by Captain Greene, is 
heavier than many observers would assume it to be, and the 
percentage to be added for the weight of animals will vary 
with the nature of the traffic, being greater with the light 
and less with the heavy traffic. His estimate beins^, that on 
Fifth avenue, which carries 91 per cent light traffic, the ad- 
dition should be about 85 per cent for the horses, while on 
Wabash avenue, w^here but 25 per cent is light traffic, the 
addition should be only about 40 per cent. The effect of the 
horse's shoe upon the street surface is modified by the nature 
of the pavement. Probably sheet asphalt suffers as little 
from it as any known form of wearing surface, unless the 
blows fall successively upon the same place and thus effect a 
displacement of the material. The bowlder is seldom scarred 
by it, hence the material of the cobble stone pavement is 
practically indestructible from this cause. Granite blocks 
are spall ed and rounded until they assume the form of bowl- 
ders, and, if very hard, become exceedingly slippery and af- 
ford insecure footing. Brick pavements would be rapidly 
destroyed were the bricks as widely separated as granite 
blocks usually are, but being placed in close contact, there is 
little room for the rounding away of corners. The brick 
surface is, how^ever, affected as it would be by receiving a 
like blow from a cutting tool or chisel of similar form. 
From this cause, will result by far the greater portion of the 
wear, since the pavement, when unbroken, will be sufficiently 
smooth to present but slight obstacles to the rolling upon it 
of the wheels of vehicles, and it will suffer comparatively 
little from that cause. The blow delivered by the animal's 
shoe will be greatly increased at high speeds. It would. 



BRICK FOR STREET PAVEMKNTS. 47 

therefore, appear to be proper, that upon avenues carrying 
suburban travel, a census of traffic should take cognizance of 
the element of speed. 

The Probable Durability of a Brick Pavement. 

This chipping or abrasion of the surface by the shoes of 
animals traveling upon it will be its severest trial, and since 
no definite statistics are available by which to compute the 
traffic tonnage to which it will be subjected, and no test has 
been made which serves as an actual measure of the wear 
of a pavement under a given tonnage, the probable durabil- 
ity of this street can not be stated, but can only be predi- 
cated upon the endurance of the brick as compared with the 
granite. Judging this street by others upon which the cen- 
sus of travel has been taken, it seems fair to assume that the 
traffic will not greatly exceed 60 tons per foot of width per 
day, including the weight of horses, which will probably 
embrace one-half of it. The surface of a granite block 
pavement, as ordinarily constructed, is about 75 per cent 
granite, while a brick pavement is about 90 per cent brick. 
There is, therefore, about 20 per cent more brick than gran- 
ite to resist wear. The brick surface is comparatively 
smooth, while the granite is uneven. Wheels will roll 
smoothly over the brick, while they will jolt over the granite 
with a continual succession of blow^s. Let it be assumed 
that the wear due to horses on the brick will be 120 per cent 
of that due to the same cause on the granite, and the wear 
due to vehicles on the granite is 200 per cent of that due to 
the same cause on the brick : it follows that the total ef- 
fect on the brick is but 80 per cent of that on the granite. 
]^ow we find in table 'No. 7 the loss of the brick in our 
abrasion testtobe 2.2 times that of the granite; a traffic, there- 
fore, which wears off one inch from the granite pavement 



48 BRrCK FOR STREET PAVEMEXTS. 

will wear one and two-thirds iiiehevS from the brick; or, 
the time required to wear an iucli from the brick will be 
about 60 per cent of that required to wear an inch from 
the granite. Xo record is known to exist showing that 
amount of wear from a granite block pavement under a 
similar traffic, but about live times the tonnage has worn 
some portions of our city pavements to about that depth 
in four years. The estimated traffic is about 60 percent of that 
on Fourth street between Walnut and Race streets, exclud- 
ing street cars, and quite similar in character, taking the en- 
tire width of pavement (omitting car tracks), and live years' 
w^ear has been estimated to have reduced the blocks one- 
fourth of an inch. This would seem to justify the belief 
that this pavement should be in fair condition after ten years' 
traffic shall have passed over it. 

Municipal Methods. 
A cause for tlie lack of deiinite statistics upon these 
matters is apparent when inunici[)al methods are considered. 
American civil engineers have achieved a world-wide repu- 
tation for the boldness and originality of their designs, the 
skill exhibited in their execution, and the economy shown in 
attaining results. Great industrial establishments have been 
built, lines of transportation, with all the works appertain- 
ing thereto, have been by them located and constructed, and 
they are accredited with being well toward the van, and of 
contributing their full share toward the progress and devel- 
opment of the country. In all such w^orks facts have been 
collected and compiled, so that reliable data is available. 
Manufacturers are willing to guarantee a given mileage for 
their steel rails or car wheels, or a given strength for their 
iron and steel, from data made available by engineers, but in 
municipal matters the conditions or the results are in noway 



BRIOK Full STRKET PAVEMENTS. 40 

similar. The total amount of money annually expended by 
the municipalities of the country in opening, improving, 
cleaning, and repairing streets and highways, is an enormous 
sum, exceeding that applied upon all other public works in 
an equal length of time. The greater part of this fund is 
nominally disbursed under tlie supervision of engineers, but 
the results are not such as to add materially to the renown 
of the profession, or to supply exact data for their guidance 
in present or future works of this character. One reason for 
this appears to be found in the fact that these funds furnish 
the greatest of the existing causes of activity in local pol- 
itics. Municipal statesmanship is developed in levying, 
watching, and disbursing this money. Laws providing for 
its collection, control, and disbursement have been enacted, 
termed the municipal code, which is more complex and pe- 
culiar than any other system known to man. Boards and Bu- 
reaus, Councils and Commissioners, Supervisors and Direct- 
ors, Counselors and Barristers, have been created or called to 
govern the work, guard the public interest, acquire fame, and 
enjoy the advantages accruing to exalted official position. The 
pervadingspirit of freedom abroad in the land being averse to 
the creation of such a class as controls similar matters on 
the continent of Europe, the rights of the people are sought 
to be preserved by the checking and balancing of sovereign 
and independent departments. When new things are to be 
done, additional statutes are enacted and more boards pro- 
vided. One authority will make an improvement and an- 
other will dig it up, while no one will repair it because the 
courts have not decided the question as to which fund shall 
be drawn upon for meeting the expense in cases of that na- 
ture. Volumes of annual reports from the heads of the sov- 
ereign departments and chiefs of the multitudinous bureaus 
into which they have been sub-divided, assure a confiding 



50 BRICK FOR STREDT PAVEMENTS. 

public, that, since the advent to power of the present incum- 
bent, the affairs under his control have been conducted upon 
strictly business principles, thus enabling him to grant more 
permits and file a larger number of papers than had ever be- 
fore been handled by similar ofiicers in a corresponding 
length of time. When the balance of power between po- 
litical parties is indefinite, and changes in official stations 
become so frequent as to make employment uncertain, it 
is sometimes found expedient to further revise the stat- 
utes and make non-partisan boards, who then carefully di- 
vide the appointments and perquisites between contending 
parties, accurate data for the making of such partitions be- 
ing always available. The smaller municipal organizations 
copy the '^ systems" of the larger ones. 

Under such regulations no very considerable amount of 
" engineering " is required. A " chief engineer " of suitable 
political complexion is chosen to sign the necessary papers, 
to whom matters not well understood by other parties can be 
referred and reported upon, and who can be blamed when it 
becomes absolutely necessary to locate responsibility some 
place, and who is willing to allow officials and other influ- 
ential parties to appoint his assistants, clerks, rodmen, and 
superintendents. Men who have acquired skill and experi- 
ence in the construction of works under different regulations 
seldom take kindly to this order of things, and the field is left 
free to such as enjoy the surroundings. Many careful and 
painstaking men are engaged in city work who would make 
excellent records were they not handicapped by the regula- 
tions governing them, and almost the entire number are 
like the parents of heroes, " poor but respectable." Having 
little at stake except their integrity, that is manfully cher- 
ished. Occasionally an erring brother may fall, but he 
merely drops from the ranks which close in his place. The 



BRICK FOR STREET PAVEMENTS. 51 

ainmunition of the enemy, which is most dangerous, espe- 
cially to those of limited experience, is flattery. ISTot one 
person in ten thousand of those having experience upon 
public works would ever approach an engineer with money 
or a valuable consideration for corrupt purposes, but if the 
insidious agent can induce him to believe that his genius is 
apparent to all, and that the world, especially the official 
part of it, will soon be shouting his praises, such influences 
may cause the young man to make himself ridiculous. But 
there is a great following who have a sufficient knowledge 
of surveying to enable them to handle field instruments, set 
out work, and compute quantities, who have but little taste 
for such study or investigation as is necessary to acquaint 
them with materials, or render them skillful in designing or 
constructing engineering works ; and their appears to be a 
greater demand for these persons on municipal, than upon any 
other class- of public works. This is probably because they 
have more leisure for compiling political statistics than 
others, are less liable to have bothersome opinions about 
how things should be done, and can more readily discern 
the grade and character of improvements desired by those in 
power or opposed by those 7iot in power, which is usually the 
same thing; it being always understood among municipal 
statesmen that an election or appointment to office confers 
upon the recipient of such honor all the necessary knowl- 
edge and experience required, not only to choose an engineer, 
but to tell him what to do, and just how to do it. Many re- 
cruits are obtained from those estimable young men annu- 
ally graduated from our technical schools and colleges. The 
learned professors solemnly announce to such of their stu- 
dents as have pursued certain lines of study, that they are 
now civil engineers. The young men very properly have 
great confidence in their teachers, and believe what is told 



52 BRICK FOR STREET PAVEMENTS. 

them to be literally true, but when they go abroad in the 
world and learn that what the professors really meant was, 
that they were qiialitied to obtain employment upon public 
works, where, by continual study and actual practice, they 
could become engineers; the shock is very great, many never 
recover, and some are engaged by municipal corporations. 
Such as do recover are achieving great success in professional 
work. 

The number and sovereignty of the departments, the 
uncertainty of the laws (for no one dare hazard any thing 
more than an opinion regarding the rule of action prescribed 
by a statute until the court of last resort has guessed at its 
meaning), and the strifes of contending factions have pro- 
duced conditions so different from those which would ap- 
pear to be proper that heroic measures may be required to 
effect desirable changes. Unless the people at large can be 
induced to look upon the matter of municipal government as 
a grotesque absurdity which is really being enacted at their 
expense,.as it is, the code will continue to be enlarged and the 
Boards multiplied. When they induce the law makers to re- 
peal the thousand and one statutes w^hich now exist, and 
enact a plain, concise code of rules, and not amend it, which 
will place the direction of public works under a single de- 
partment, with uniform regulations in like municipalities 
throughout the state; placing the designing and manage- 
ment in the haiids of a corps of engineers who should ac- 
quire position and promotion by the record of their achieve- 
ments, and not by reason of race, creed, or previous con- 
dition of partisan servitude or influence, and who, being un- 
trammeled as in the world at large, would succeed or fail by 
merit alone, the principal of natural selection, or the survival 
of the fittest, would soon place the direction of such works 
in systematic order under competent control. Then would 



BRICK FOR STREET PAVEMENTS. 5o 

streets be built to remain undisturbed, as the bottom layers 
or drains and pipes would first be put down and carried to 
property lines, then would the character of the pavement be 
adapted to the uses to which it would be subjected. Paving 
companies would construct streets and guarantee them to 
lemain in proper form and repair until a speciiied tralRc ton- 
nage should have passed over them. Manufacturers would 
furnish materials under like conditions. Order and uniform 
system would exist where chaos now reigns, and legislative 
interference would cease to trouble executive business. 

Probably the view is Utopian, and will never be realized 
until we pace those golden streets, but the patching remedies 
and special laws continually being enacted forthe betterment 
of evils known to exist are only adding complications to 
complex affairs, and it thinking people are induced to direct 
their attention to a subject of such universal and vital inter- 
est, and make an effort in unison to better municipal govern- 
ment as applied to public works it will certainly result in 
some good. Politicians and bosses will undoubtedly offer 
great obstacles, but the mere absurdity of present methods 
will insure a change, and if engineers were accorded similar 
freedom and control, with such responsibilities and oppor- 
tunities as are given them upon other works, they would not 
ignore so inviting a field as that presented by the needed im- 
provements in these matters. 

General Discussion of Pavements. 

The office of a street pavement is to provide a w^earing 
surface which shall fulfill the following conditions : 

First. It must present a secure and pleasant footing for 
animals. 

Second. It must have sufficient smoothness to render 
traveling in carriages agreeable, and traction easy and as nearly 



54 BRICK FOR STREET PAVEMENTS. 

noiseless as is practicable, for all descriptions of wheeled ve- 
hicles (excepting those provided with, flanged wheels). 

Third. It must be of such form and material that liquids 
falling upon it will quickly flow from it into proper conduits, 
and must furnish no permanent lodgment for street filth of 
any kind. 

Fourth. It must be capable of sustaining without change 
of form, any and all loads usually transported on public 
highways. 

Fifth. It must be reasonably durable, both as against 
the attrition of street traffic, and the destroying or dissolving 
action of the elements. 

Sixth. It must be economical. That is to say, sufficient 
comfortable use must be obtained from it to make it worth 
both the cost of construction and maintenance, 

Seventh. It must be capable of removal and replace- 
ment, or repair from failure at reasonable cost, and with 
materials and appliances within the control of the street re- 
pairing department. 

A study of these conditions at once reveals the reason 
why the ^' paving problem" is of such an intricate nature 
that it has so long remained unsolved, as well as a cause for 
so many unhapp}^ failures in its attempted solution. 

For the first and second conditions, the dirt road in good 
repair stands without a rival, but it meets no other require- 
ment, hence its use is i-estricted to race tracks and country 
roads, which like canals are only navigable when the weather 
conditions are favorable. 

For the second, third, and fourth conditions, the asphalt 
pavement on proper foundation appears to be better fitted 
than any other that has come into such general use; but 
many persons say that it does not properly meet the first re- 



BUICK FOR STREET PAVEMENTS. 55 

quiremeiit, criticise it severely as to the fifth and sixth, and 
aflirni that it utterly fails to meet the seventh. 

Stone block pavements meet the first requirement, but 
indifferently; utterly fail in the second and third, when 
properly constructed; are better adapted to comply with the 
conditions of the fourth, fifth, and seventh, than almost any 
other description of city street, but when a high charge for 
transportation is to be added to the cost of preparing the 
material, they fail to meet the sixth condition. 

Wooden block pavements meet the first, second, fourth, 
and seventh conditions fairly well, when made of suitable 
materials well combined ; but, as they have been built in this 
country, have signally failed to meet the third condition, and 
have fulfilled the fifth and sixth but very indifferently. 

The bowlder or cobble-stone pavement has been with us 
so long, and has been treated so badly, that familiarity with 
it has bred a species of contempt that is hard to overcome. 
It has become popular to consider it an all around failure, 
yet it meets the first and seventh conditions fairly well, and 
so far as the material is concerned, it stands unrivaled in the 
fifth. In many of our cities where horse cars have been 
operated for the past twenty or thirty years, and the street 
railway companies are required to maintain the pavements 
within their tracks, the bowlder pavements are still retained 
between the rails, while the residue of the streets have been 
paved with other materials, because in that position they are 
said to meet all of the conditions named, excepting possibly the 
second and third, better than any other substance yet offered 
for the wearing surface of roadways. This saying, however, 
does not appear to be any thing more than an expression of 
opinion, which can not be sustained by any process of rea- 
soning. The cobble-stone can be given no definite bearing 
on any foundation ; it can not be held in position by any bond 



56 BRICK FOR STREET PAVEMENTS. 

that can be given it in construction. It does not present a 
suitable surface for vehicular travel, or that can by any pro- 
cess be ke[)t free from filth ; yet it does not wear out, is easily 
restored if loosened from its place, and it does answer very 
well for street car horses to travel upon. 

Broken stone or macadam as commonly used, of mingled 
limestone and shale, meets none of the requirements. If,. 
however, it is clean refractory material, properly prepared 
and combined by rolling, it fulfills all the conditions except 
the third (and even that reasonably well), providing the traffic 
is moderate, and the repairing is promptly and efficiently 
done. It may be set down as an established fact, however, 
that wh'en a macadamized street is dug into for any purpose 
that it is never properly replaced. 

No one of these conditions can be entirely ignored, yet 
it is obvious that no pavement yet devised, fully meets all of 
them. Could the first be ignored, it would be an easy mat- 
ter to cover street surfaces with iron or steel plates that 
would fully meet all the others, but plainly this can not be 
done. The surroundings of the pavement and the extent and 
nature of the traffic to which it is to be subjected, must be 
considered in order to decide which of the conditions 
shall be allowed to determine its character. The first, that 
of furnishing a secure and reasonably comfortable footing 
for animals, can in no case be ignored, and in many instances 
must control all other considerations. Wherever the pave- 
ment is to be used as a thoroughfare for vehicular traffic at 
fair rates of speed, or when time, pleasure driving, or quiet- 
ness become elements of importance, then the first and sec- 
ond conditions must be met, and other features may or may 
not be caused to yield to their requirements. But the pres- 
ervation of life and health is the essential cause of business 



BRICK FOR STREET PAVEMENTS. >) ( 

activity, hence the third condition, that of maintaining cor- 
rect sanitary conditions, should never be neglected. 

To those at all familiar with street construction, it is 
obvious that the wearing surface, or pavement proper, can 
not, and does not in itself, support the loads brought upon it, 
hut that it more or less successfully resists the impact and 
abrasion incident to the traffic, and transmits the weight di- 
rectly to the bed or foundation upon which this surface ma- 
terial has been placed. It follows, therefore, that the fourth 
condition can be met by any description of paving material 
which has sufficient hardness to retain its form under the 
pressure of street traffic, by merely placing it on a properly 
prepared foundation; and further, that unless the pavement 
shall be placed upon a bed capable of sustaining under all 
conditions the loads brought upon it, the surface will yield 
regardless of the material of which it is composed, and that 
this condition not being complied with, no essential feature 
of a good street surface will remain. Failure to meet this 
condition is the error most commonly committed in the build- 
ing of pavements. In this latitude the winter frosts pene- 
trate to a depth of from one to three feet, or, when not acted 
upon by frost, the subsoil drainage is seldom so thoroughly 
efficient as to prevent the changing of the ground from a 
firm unyielding soil to one of almost complete saturation, 
thus materially affecting its sustaining power. It therefore 
follows that no pavement wh:ch is to be subjected to a heavy 
traffic at all seasons of the year can be relied upon to retain 
the form originally given it, unless the foundation or bed 
upon which it is placed shall either be carried below the ac- 
tion of the frost, say three feet or more, or be so constructed 
as to distribute the weights of passing loads over sufficient 
areas to enable a comparatively weak subsoil to sustain 
them. The deep foundation is the ancient, and undoubtedly 



58 BRICK FOR STREET PAVEiVIENTS. 

the most durable method, having apparently been the ordi- 
nary practice with the Romans, but the distributing coating 
is far more economical, and hence has become the established 
modern practice. 

Two methods are in vogue. First, to drain the sub- 
roadway as efficiently as is practicable, grade it to the proper 
form, compact its surface by rolling, and cover it with a 
layer of mingled broken stone and gravel, which is made 
smooth and firm by flooding and rolling with a steam roller ; 
the layer of metal being from six to twelve inches in thick- 
ness, according to the requirements of the locality or the 
specifications. On this layer or "foundation" is spread the 
bed of sand, in or upon which the pavement is set. Some- 
times broken stone alone, and again gravel only, is used for 
the bottom course. This style of " foundation " is used very 
extensively for all descriptions of pavements excepting as- 
phalt. With brick pavements the practice of placing a layer 
of bricks flatwise on the bed of sand, covering them with a 
thin coating of sand, and paving on it the wearing surface 
on edge, is quite common, and produces what is called the 
"two course" pavement. Still another method consists in 
covering the layer of sand with tarred boards, upon which 
the sand cushion and brick on edge are paved herring-bone 
style, producing the "Hale Pavement." In this, however, 
the broken stone is generally omitted, the boards being sepa- 
rated from the subsoil by from four to six inches of sand 
only. These expedients tend to better the distribution 
of the weights brought upon the pavement, and have the 
merit of economy in first cost, but they are obviously inade- 
-quate except where the subsoil is exceptionally good and the 
traffic very moderate. The method of combination is quite 
defective. When gravel is used that is free from loam, it 
will not compact under the roller, and if it does contain 



BRICK FOR STREET PAVEMENTS. 59 

loam the water which comes from the subsoil, and percolates 
throii2^h it, is liable to carry the soluble substances with it 
down the gradients, and leave the pavement unevenly sup- 
ported. When broken stone and gravel, or broken stone 
alone, forms the foundation course, it is expected to be por- 
ous, and act, to some extent, as a subsoil drain. The voids, 
however, are liable to become the receptacles of the clay 
from beneath, which is brought uj), or rather the stones 
brought down, by the pressure upon the pavement, or they 
will be tilled b}' the sifting down of the bedding course of 
$<and, caused by the jar of the travel, and this escape of the 
sand will leave the blocks unevenly supported. All of the 
varieties described in this first method are extensively used, 
and are made more or less expensive and durable, or cheap 
and temporary, as they are carried to greater or less depths, 
and as the w^ork is thoroughly or carelessly done. But they 
are so constructed that natural causes would alone destroy 
them in a comparatively brief space of time, and when the 
forces of nature are aided by the disturbances to which the 
sub-grade of the street is ordinaril}^ subjected, and the traffic 
upon the pavement, it follows that the life of such a founda- 
tion seldom exceeds the duration of the wearing surface, and 
the failure of the former very frequently accelerates the de- 
struction of the latter. - 

The second method consists in preparing the subsoil by 
grading and rolling as before described, and placing upon it 
a layer of hydraulic cement concrete to serve as a founda- 
tion for the pavement. For equal volumes, the cost of the 
<joncrete is about three times that of the broken stone or 
gravel; but from one-half to two-thirds of the amount is 
required, hence the expense of the concrete foundation is 
one and a half to twice that of the broken stone or gravel. 
When properly made and undisturbed, it will not yield to 



60 BRICK FOR STREET PAVEMENTS. 

the action of the weather, and the renewal of the pavement 
need extend to the wearing surface only. The expense of 
cutting through and replacing the concrete when the street 
must be opened for any purpose, is much greater (perhaps 
two to three times) than in the other forms of foundation, 
but such work can be done without serious injury to the re- 
mainder of the street; and when repairs are properly made 
the opening of the pavement and its foundation is less in- 
jurious to the street having a concrete foundation than the 
one that has it not, because the concrete base will support 
the pavement over small cavities, while the broken stone or 
gravel will sink into them. 

The thickness of the concrete varies with the require- 
ments of tlie traffic, and other conditions, from four to 
eight or more inches. The ordinary practice is to use nat- 
ural cement in its composition, and make the coating six 
inches in thickness for roadways of medium traffic without 
car tracks. The condition of the subsoil should, however, 
be considered in determining the depth of concrete, for 
where it is soft or spongy, or trenches are to be spanned, a 
greater amount will be required. A concrete foundation, is 
an absolutely necessary beginning for any really good and 
durahle street pavement, and even for work of medium 
character and price it is economical. Pavements of sheet 
asphalt are always placed on concrete foundations, the wear- 
ing surface being separated from the cement by a cushion 
coat, ordinarily about half an inch in thickness. 

Htone, asphalt, wooden, block, or brick pavements, are 
usually placed on a layer of sand from one to two inches in 
thickness over the concrete, but the practice regarding the 
cushion coat is by no means uniform, varying from an actual 
bedding of the blocks in the cement mortar to two or even 
three inches of sand, but the general custom in this country 



BRICK FOR STREET PAVEMENTS. Gl 

■appears to be in favor of the sand cushion. Convenience in 
■construction and repairs and the theoretical elasticity of sur- 
face being in favor of that combination. The choice of the 
sand to be used is of more than ordinary importance, since if 
it contains a considerable percentage of soluble substances, 
or is alternately coarse and fine in different places, disphice- 
ment is likely to occur, and the pavement will become 
uneven. 

All block pavements, whether of stone, wood, asphalt, 
or brick, should be as closely placed as is practicable, and 
the interstices filled with a non -absorbent material. Possibly 
a narrow spacing may be required on gradients paved with 
sawed wooden blocks to furnish footing for animals, but the 
wide spacing ostensibly for this purpose so frequently seen in 
all these varieties of pavements is undoubtedly bad practice, 
since it so materially reduces the resistance of the material 
composing the wearing surface, facilitates the chipping from 
the angles, and produces an uneven, noisy street, with cavities 
to receive and retain filth. 

What Shall be Specified. 

The writer has seen no specifications for brick pavements 
which either clearly or fairly describe the material to be used, 
so that manufacturers or bidders can know just what will be 
required upon a given work. The majority of the specifica- 
tions recite that " the brick to be used must be hard, free 
from defects of any kind, manufactured and burned espe- 
cially for street paving purposes, be equal in all respects to 
the sample filed with the proposal, and subject to inspection 
and acceptance or rejection by the engineer or inspector." 
With our present knowledge of this material, this phraseology 
may be accepted, but in reality it specifies very little. Its 
acceptance or rejection by an engineer is ordinarily regarded 



t)2 BRICK FOR STREET PAVEMENTS. 

by the corporation as a safeguard, but no parties entering- 
into a contract can place a power that is wholly arbitrary 
and undefined in the hands of an engineer, who is in reality 
the executive agent of one of the parties. Because bricks- 
have been manufactured and burned especially for street 
paving purposes, does not necessarily fit them for such use; 
the term hard is an indefinite one, and without stating what 
constitutes defects, there may be difierences of opinion as to 
whether or not they exist in a given article as well as to the 
equality of goods furnished with sample exhibited. Even 
sample paving bricks have been known to be worthless for 
street paving. The characteristic qualities and strength of 
the material are not clearly set forth as they should be. The 
power to accept or reject is left undefined, which should 
never be the case, neither manufacturer, bidder, nor tax-payer 
should be bound by the action of an engineer, unless that ac- 
tion shall be in accordance with known provisions and fixed 
rules. With the hope, therefore, of adding something to the 
information needed for bettering specifications in this re- 
spect, let us examine our work as tabulated. 

From Tables IN'os. 1 and 8, we might select a chemical 
composition quite suitable for the purpose, but there are such 
wide variations in clays that it w^ll probably be advisable not 
to be too definite in specifying ingredients. Silica may con- 
stitute from sixty to seventy-five per cent ; alumina, from fif- 
teen to twenty-five ; irou, from five to ten; while lime and 
magnesia should neither exceed two per cent; and the al- 
kalies should be from one to two per cent. The form and 
proportions in which these ingredients are present, and the 
difierence in results obtainable by variations in methods of 
manufacture are so great, that it will evidently be better to 
define the qualities which are required, and leave the manu- 
facturer free to produce them in his own way. Lime can 



BRICK FOR STREET PAVEMENTS. 63 

be readily detected, and an excess of that ingredient might 
properly be prohibited by the specification. 

With suitable ingredients, properly combined and burned, 
the percentage of absorption will be small. An inspection 
of Table ISTo. 2 shows that it varies greatly, indicating a lack 
of uniformity in results, w^hicli is to be avoided, or failure will 
result. The absorption should, therefore, be placed at the 
lowest limit which can be designated without excluding such 
bricks as are known to have withstood other tests credit- 
ably. I would recommend iiaming two per cent as a 
maximum. 

Specific gravity depends to some extent on the density 
of the material, and should, therefore, be as high as is ob- 
tainable with this material. Two and one-tenth might be 
named as a minimum, with credit for excess, as about two 
and three-tenths is attainable. 

The crushing strength determined from two inch cubes, 
prepared and treated as set out in describing the tests show^n 
in Table 'No. 3, should not be less than 12,000 pounds per 
square inch. This might be named as the average crushing 
strength, the limit of variation of any sample not to exceed 
twenty-five per cent below. 

The modulus of rupture, as determined by the formula 
used in calculating Table No. 4, from tests of transverse 
strength, could properly be fixed at 1600. 

Tables No. 5 and 7 would indicate that unless a rather 
liberal allowance be made in the matter of abrasion as com- 
pared with granite, manufacturers may complain that many 
are called but few are chosen. One-third of the competitors 
in this test would be among the saved by placing the limit 
at tw^o and two-tenths times. It Avill be safe, therefore, to say 
that in any tests for determining the comparative loss of the 
brick under abrasion and impact, as compared with Lithonia 



64 BRICK FOR STREET PAVEMENTS. 

granite, the loss in weight of the brick shall not be more 
than two and one-fourth times that of the granite. 

Cniformitj in size and texture appears to be attainable, 
and lack of it produces many undesirable diJQiculties. Wide 
variations in size result from faulty drying and burning. We 
must either specify how the drying of the brick and the tiring 
of the kiln shall be done, or describe what we want as the 
product of the kiln, and insist upon getting it. In the pres- 
ent state of our knowledge the safer plan will be to name 
the requirements and leave the manufacturer to wrestle with 
details. 

The amount or percentage of contraction in drying and 
burning varies with the different clays from one to twelve 
per cent. With the coal measure lire-clays it is usually 
about two or three per cent, while with the plastic clays and 
river silt it is very much greater. Excessive contraction 
is obviated to some extent by adding to the mixture ground 
burnt cla}' and a fusible sand. Unless other ingredients are 
present to obviate such a result, these components are liable 
to produce brittleness. In modern down-draft kilns with 
clsiys which do, and should contract as much as three per 
cent, rapid tiring sometimes produces bricks from the upper 
courses, on which the flame acts directly, that are actually 
larger than the molds in which they have been formed. It 
follows that such bricks are much checked and cracked, ren- 
dering them untit for use, but the cause is apparent. The 
contained moisture in the partially dried brick is expanded 
by being first turned into steam, and, while in this condition, 
the outside of the brick is fused, thus permanently fixing its 
exterior form and dimensions, except as modified by checks 
and fire cracks. Other bricks in the kiln, made in the same 
molds, will be shrunken to the full extent of their contrac- 
tilit}', thus producing not only a troublesome variation in 



BRICK FOR STREET PAVEMENTS. 65 

size, but likewise Avide differences in quality. These defects 
can be remedied by a gradual and continuous firing that will 
produce and permit the natural amount of contraction 
throuo:hout the kiln. Absolute uniformity in size is not 
practically attainable, but a much nearer approach to it than 
is now common can be reached by specifying a minimum al- 
lowable deviation and rejecting material that does not com- 
ply with the requirement. I would suggest two per cent 
as the maximum allowable variation from the standard di- 
mensions adopted. 

Assuming that the clay has been properly ground and 
mixed, uniformity in texture is obtainable only by conducting 
the burning in a suitable manner, continuing it to a sufficient 
degree, and no longer, and then allowing the kiln to cool 
down without permitting drafts of cold air to come in con- 
tact with the bricks until their temperature has fallen below 
the boiling point of water. The degree to wdiich the firing 
should be extended is ordinarily termed " complete vitrifica- 
tion," but would appear to the writer to have been very un- 
happily chosen. To " vitrify '' is ordinarily held to signify 
*' turning into glass by the action of heat," which is not the 
desired result in this case. The term having been adopted by 
common consent, the meaning which defines the process 
must be given it, and w^ould appear to be, that the alkalies 
and alkaline earths shall form vitreous compounds with the 
iron and more readily fusible silica, so as to give the brick a 
dense, uniform texture, obliterating the granular appearance 
completely, but not fusing or melting the brick so as to in- 
jure its form or exterior. This result is obtainable only by 
progressive firing to the right extent, but with the manufac- 
turer it is like Major Jones's exercises, the fine point consists 
in knowing just wliere to stop. In this particular feature 
the fire-clays are claimed to be superior to the shales and 



C)G BRICK FOR STREET PAVEMENTS. 

silts. The latter are more readily fused than the former, and 
when the melting point is reached the bricks sometimes lose 
their form and melt together. To avoid danger from this 
source sudden cooling is resorted to and the product is ren- 
dered practically worthless by the brittleness which results 
from such a course. It is claimed that the fire-clays can be 
held at a sufl5.ciently high temperature to produce the re- 
quired " vitrification " without danger of melting together, 
and hence furnish the most reliable product for street paving 
purposes. Our investigations appear to point to the conclu- 
sion, that from neither clay has that uniformity of product 
been attained which is desirable, and that can and must be 
made before reasonable certainty in strength and durability 
can be assured; for among the tire-clay bricks many are 
found that show scarcely any indications of fusion or " vitri- 
fication " at all. Many more that are but partially fused or 
" vitrified," the exterior portion being dense and non-ab- 
sorbent, while the interior, marked by concentric colored 
rings, surrounds a central portion of open granular texture, 
and still others present a closed metallic or granitic texture 
throughout. By firing and annealing in a proper manner, 
uniformity in texture without brittleness can be produced 
from any clay that is suitable for the manufacture of bricks 
for street paving. These qualities should be specified, and 
such manufacturers as can not and do not produce them, 
should not find sale for their goods, because the hopeful 
young industry will soon perish or be relegated to the smaller 
interior cities and towns, unless these essential qualities are 
produced. It may be asserted that such requirements Avill 
increase the cost of production. If need be let it be so, but 
such as furnish the required product will find a continued 
and increasing demand for their goods, giving a permanent 
value to the plant, and the only additional expense necessa- 



BRICK FOR STREET PAVEMENTS. 67 

rily involved would a})peiir to be more time and care de- 
voted to the biirniii2: and coolino:. 

The following is suggested as an addition to the specifi- 
cations, and as more knowledge is acquired, further revision 
may be necessary. 

"The bricks or blocks to be used for paving shall be 
straight, smooth, and free from checks or fire cracks. The 
corners shall be rounded to a radius of one-fourth of an 
inch. In size they shall not vary more than two per cent 
in any dimension from the standard adopted for the kind of 
bricks or blocks to be used. When broken, the fracture 
shall be smooth and straight, not conchoidal ; and the text- 
ure of the block shall be uniform throughout, and not gran- 
ular. The amount of moisture absorbed when tests are 
made either with the whole block or pieces, shall not exceed 
two per cent of the weight of any sample when continuously 
immersed for three consecutive days. E"o bricks will be ac- 
cepted which contain lime or other soluble substances in 
sufficient quantities to cause spalling or pitting of the sur- 
face when soaked in water for three consecutive days and 
then exposed to the air for a corresponding length of time.. 

" When the bricks shall have been delivered upon the 
roadway, samples may be selected at random therefrom for 
testing, which must meet the following requirements : The 
average crushing strength of two-inch cubes taken from any 
part of the brick shall not be less than 12,000 pounds per 
square inch. 

" The modulus of rupture for transverse strength shall 
not be less than 1,600 pounds when calculated by the for- 
mula, 

3 W Z 
R= 



2 6d2 



68 



BRICK FOR STREET PAVEMENTS. 



R being modulus of rupture, W=:load in pounds, ^^^rbreadth, 
(;/=depth, and ^:=length, all in inches. 

^' The specific gravity shall not be less than two and 
one-tenth when determined by the formula, 

W 

Specific gravity= 



W^ — W^^ 

Where W=:w^eight of specimen freed from moisture before 
immersion, W'=:weight of same after seventy-two hours' 
soaking, and W=w^eight of same in water. 

'' In any test for determining the resistance to abrasion 
and impact, the loss of the brick shall not exceed two and 
one-fourth times that of Lithonia Georgia granite when 
subjected to like test. 

" The material shall be subjected to inspection by the 
engineer placed in charge of the improvement, who will se- 
lect samples, not exceeding live in number, for each of the 
tests required for determining absorption, crushing strength, 
transverse strength, and abrasion and impact, and cause the 
necessary specimens to be prepared, the tests to be made, 
and will accept or reject the material in accordance with the 
results of such trials. An allowance of twenty per cent may 
be made for variation of single specimens, but the average 
results shall be in accordance with the provisions herein set 
forth, or the material must be rejected, and removed at the 
contractor's expense. The tests may be repeated upon the 
arrival of different shipments, as frequently as may be nec- 
essary to insure the acceptance of only such material as shall 
comply with the provisions of this specification." 

What Has Been Done. 

Bidders w^ere informed that proposals would be consid- 
ered for any of the varieties of brick which had been tested, 



BRICK FOR STREET PAVEMENTS. 69 

but that such as showed a crushing strength of less than 
10,000 pounds per square inch, or a loss in the rattler test of 
more than three times that of the granite, would probably 
not be adopted. When the bids were opened it was found 
that proposals included Nos. 5, 6, 13, and 14 only, and the 
contracts were awarded for using l^o. 14. Subsequently it 
was decided to pave about 300 or 400 feet in length of the 
south end on the south contract with Nos. 5 and 6, and a 
corresponding length on tiie south end of the north contract 
with Xo. 13, which has been done. 

The form given to the roadway is shown in the accom- 
panying sections. Figure 1 showing the street where occu- 
pied by street railway tracks, and figure 2 the section where 
no tracks were placed. Figure 3 is a full-sized section of 
the rail adopted. This was placed directly on the tie, or 
rather on a bearing plate but three-eighths of an inch in 
thickness, spiked directly to the tie ; each alternate plate 
having an outside brace to aid in holding the rails to guage, 
thus obviating the necessity of using any other appliance to 
eifect that purpose. In surfacing tracks, the rail of each 
track nearest the center line of the street was placed one 
inch higher than the opposite rail of the same track. Tem- 
plates w^ere used for forming the sand bed on which the 
pavement was placed. Figure 4 shows that used for the 
the central space between tracks; figure 5 the one for the 
tracks, and figure 6 that for the spaces between car tracks 
and curb-stone. It will be noticed that the template used 
at the sides differs slightly from the form specified in the 
cross-section of street, but this variation is believed to be a 
betterment, being in the nature of a camber against the 
greater weight of trafiic, and tending to confine the water 
near the curb. 

Stakes were given for the alignment and grade of tracks, 



70 



BRICK FOR STREET PAVEMENTS. 



•auiq 



loaj^S 




^jaaiiao 



CRICK FOR STREET PAVEMENTS. 





Fi{,' 



72 



BRICK Foil STREET PAVEMENTS. 



<„n;R^ 



uVV 



Mm 









i ,MM^ 



BRICK FOR STREET PAVEMENT3. 78 

and wliere no tracks were laid, levels were given from the 
curbs for forming the concrete and bed for the pavement. 
The resulting form of street has less crown than is usually 
given to streets paved wnth brick, but it is pleasing to the 
eye, the entire surface is available, and it is believed that it 
will be more durable than it would be were the cross grades 
steeper, because there is no influence tending to concentrate 
the trafiic in lines on any portion of the roadway. 

The form of rail-head will be observed to be almost 
identical with that recommended so urgently in my report 
of May, 1889, but the base of rail and general construction 
of track is materially different. The ties are of white oak, 
5" X 7'', placed three feet between centers, excepting at rail- 
joints, where the ties are double w^idth. The joints are 
strong; splice bars being 24'' in length, fitting snugly against 
base and head of rails and being secured by six one-inch 
bolts. The pocket or space between base and head of rail 
was filled w^ith a fine concrete or cement mortar, smoothed 
with a trowel to make vertical faces against which the pav- 
ing was set. The concrete was driven under the ties with 
tamping bars, so as to secure a depth of three inches of this 
material on which they should rest. For the heavy motors 
and high speeds now used on electric roads, this depth 
should be increased, but when no part of the expense of such 
foundation is borne by the railway company, it appears un- 
just to increase the cost of a street improvement solely for 
that company's benefit. When grants to street railway com- 
panies are made for the use of such power, they should con- 
tain provisions for placing the tracks on suitable foundations, 
in order that stability may be obtained, and pavements not 
be endangered from such causes. 

The form of curb adopted, and the manner of setting it, 
w^ere very much criticised when the plans were first submit- 



74 BRICK FOR STREET PAVEMENTS. 

ted, as it is a radical departure from what has been consid- 
ered established city practice, but the innovation is now very 
generally conceded to be an improvement. Bottoms of curb 
stones were not required to be dressed or pitched to a line, 
and no spalling away required where variations from speci- 
fied dimensions did not exceed two or three inches. There 
was a disposition to reject pieces varying from the prescribed 
dimensions when the depth at any point Avas less than the 
specified depth. To avoid having such pieces rejected, the 
quarrymen soon learned to confine the variance to excess 
only, which resulted in getting stones of an average depth 
of sixteen rather than fourteen inches. Inasmuch as they 
had been informed that pitching to a line would not be in- 
sisted upon where stones were broken to within two inches 
of i^rescribed dimensions, the result was a rather detrimental 
excess of stone. The tile drain was generally placed twenty- 
four inches below the top ot curb and covered with sand, the 
top of which was smoothed off at just twenty inches below 
top of curb, then a foundation of concrete about four inches 
in depth was placed, upon which the curb-stones were 
blocked in position, and the residue of the concrete required 
by the plan tamped under and filled about them. This form 
of curb should reach to and be bedded in the concrete ; ex- 
cessive depth of stone merely serves to more nearly cut the 
concrete off and deprive the curb of efiicient support. If 
exact dimensions are to be insisted upon, curbs should be cut 
to them on all sides, but that is obviously a useless expense. 
There was almost constant irritation regarding the rela- 
tive elevation of the pavement and the rails of the car tracks. 
The language of the specifications upon this point is the 
following: " The bricks or blocks will be paved adjacent to 
the rails in such manner that when rammed and rolled, as 
herein before specified, the surface of the pavement will not 



BRICK FOR STREET PAVEMENTS. 75 

vary more than one-fourth (i) of an inch from that of the 
steel rails, and never be below them." For work to be done 
under similar circumstances, the last clause should read, 
"and never be aboi'e them," because, for some undefinable 
reason, this was construed to mean that the pavement was 
intended to be a quarter of an inch higher than the rail. 
Excessive ramming would drive the bricks down along the 
lines of rails, but there was no method of raising them ex- 
cept to take them up and put in sand. After being required 
to raise a few patches upon the mistaken idea that the bricks 
were too low, the pavers would raise the templates, keep the 
bed high, and endeavor to escape censure by ramming heav- 
ily along the rails, resulting in getting the surface of the 
pavement about one-fourth of an inch higher, as compared 
with the rciils, than it should be. This will verj- greatly in- 
crease the wear upon the bricks adjacent to the tracks, en- 
hance the tendency of the pavement to rise, or the bricks to 
"pop out" ^vhen shaken by passing cars, lessen the tractive 
force of the motors, add to the labor of keeping the rails 
clean, and lead vehicles to follow these incipient grooves 
along the car tracks, which the grooved rail was intended to 
discourage. I^o mention need be made in this connection of 
the causes which produced this result, since it can not now 
be obviated. Where the directions of an engineer carry 
Avith them the clear, undisturbed force w^iicli such orders 
should have, results are seldom variable, and if they are un- 
satisfactor}' the responsibility is not a divisible quantity. 
When the traffic tonnage is compared, it will be found that 
the eight inches of steel in the two car tracks carries so 
much more than an equivalent width of brick, that it is fair 
to assume that the rails will be lowered almost, if not en- 
tirely, as rapidly as the bricks will be worn down, so that 
there never is a time when a good reason can be given for 



76 BRICK FOR STREET PAVEMENTS. 

not making the surface approximate as closely as is practi- 
cable to a uniform plane. There is a much nearer approach 
to this result on Main avenue, as it is, than is found in the 
average city street, and, taken as a whole, it is believed to 
be at this time the most comfortable as well as the hand- 
somest drive which contains a double track street railway 
line in the State of Ohio, and the street car service in the 
village is believed to be as efficient, and approach as nearly 
to the ideal rapid transit, as has yet been attained by any 

suburb. 

The Matrix. 

One condition appears to be essential in the construction 
of brick or stone block pavements, which are to be either 
durable or smooth, and that is, to give each brick or block 
such efficient support, and to bind all so firmly together, 
that passing loads, wdiatever their weight, shall cause no move- 
ment of the separate pieces upon the foundation or each other. 
In brick pavements on a sand cushion this result can only be 
secured by completely filling all joints with a cementing sub- 
stance. On this work the substance used was coal-tar, or, 
as it is generally called, paving cement. Care was taken to 
keep the surface clean during the setting and ramming of 
the bricks, to sweep all spalls or rubbish from the surface in 
advance of the tar-pourers, and to project into each joint a 
stream of tar at a high temperature that should penetrate 
and fill every cavity from the sand-bed to the surface. A 
second pouring or " plugging " always followed the first, 
in order to fill such .joints as allowed the tar to sink below 
the surface to any perceptible extent, and then the surface 
was covered with clean, sharp sand. Practically, the best py- 
rometer for determining the temperature of the tar is its 
appearance. Pouring should not be allowed unless it is 
smoking hot and perfectly liquid. To assert that every one 



BRICK FOR STREET PAVEMENTS. 77 

of the millions of crevices was completely filled is not in- 
tended, since such a result would hardly be within the bounds 
of possibility, but in every instance where bricks were taken 
out after the tar-pouring had been done, they were found to 
be solidly united by the tar, and hardly a square inch of 
surface could be discovered that had not been covered by it. 
Great care is necessary in doing the tar-pouring, as the 
smearing of tar over the surface, leaving the spaces beneath 
unfilled, is much worse than omitting it entirely, as its 
.presence will prevent the sand covering from penetrating 
until the trafiic shall have rendered the surface uneven. The 
sand used for covering the pavement should be absolutely 
free from loam. It should be sharp and gritty. There 
should be a marked variation in size of the particles of 
which it is composed, and they should be sharp and angular, 
not rounded. One-fourth of an inch in depth is an abund- 
nnce in quantity, and it should be evenly spread as soon as 
the tar-pouring has been completed, so that when the tar 
sinks into the joints, if it does sink, it will carry the grit 
with it. 

A cement grouting is coming into general use in place 
of the coal-tar filling, which is preferred by many engineers, 
from the fact that hot weatlier renders the tar so nearly fluid 
that it flows toward the lower levels, and leaves the higher 
points unfilled. If made of Portland cement, and thoroughly 
slushed into all crevices, the cement would give satisfactory 
results. For a comparison between the two materials these 
conditions exist. With the coal-tar, however much it may 
be melted by heat, it reunites and becomes firm again so 
soon as the temperature falls; while with the cement, should 
the bond once be broken from any cause, it never reunites. 



78 



BRICK FOR STREET PAVEMENTS. 



Where Should Brick be Used for Street Pavements. 

Statements made in preceding paragraphs have indicated 
that the brick pavement will .not have the durabihty in lo- 
cahties where street traffic is greatly concentrated, that 
would be obtained from the greater mass, and superior re- 
sistance to wear of granite blocks. Are bricks, then, a suit- 
able paving material in any locality? Undoubtedly they 
are, when they do not absorb more than two or three per 
cent of their weight of moisture, and will withstand the wear 
of the street traffic for a reasonable length of time. In any 
city having a population less than 100,000, there are few, if 
any, streets upon which the volume of traffic is concentrated 
to such a degree as to endanger a well constructed brick 
pavement for many years. Upon streets mainly occupied by 
residences, where reasonable quiet and correct sanitary condi- 
tions are indispensable, brick are in every way superior to stone 
block pavements, and in durability; when the cost of mainte- 
nance is considered are superior to asphalt, because the latter 
form of pavement, when not used at all, will undergo changes 
which will render it brittle and practically useless, whereas 
the brick will not be similarly affected. This change in asphalt 
from exposure is probably not thoroughly understood, but it 
is acknowledged to exist, and is the principal cause of ex- 
pense in maintaining pavements made of it. Sheet asphalt 
is not worn from a pavement by the traffic to such an extent 
that it Avould require renewal during the lifetime of a gen- 
eration, but it is pressed out of position by the traffic, or 
rendered brittle by changes in its composition. Probably 
two-thirds or more of the cost of maintenance is due to the 
latter cause, which action is believed to be retarded rather 
than accelerated by the traffic upon it. In brick pavements 
the action of the weather will affect the combining materials. 



BRICK FOR STRliET PAVEMENTS. 79 

but not to an appreciable extent the bricks themselves unless 
it be defective ones which can readily be removed and re- 
placed. It follows, therefore, that the cost of maintenance 
of brick streets, when made of good material on permanent 
foundation and subjected to moderate traffic, will be less thau 
that of any other form of pavement, excepting only granite 
blocks. Brick is, therefore, a suitable material to be used 
upon a very large percentage of all paved streets, for granite 
blocks are in no way fitted for use, either upon residence 
streets or upon such avenues as lead to residence districts, 
where the driving is at fairly high speed, and should be done 
with safety and comfort. This brings brick into direct com- 
petition with asphalt as a paving material, and, while it must 
be admitted that the asphalt paving companies are deserving 
of great credit for their efforts and success in producing good 
streets, it must also be granted that persevering, honest com- 
petition will result iu public benefit if conducted on correct 
principles. The indiscriminate careless use of brick as a 
paving material will result beneficially to the asphalt inter- 
est, and disastrously to the brick manufacturers, but the con- 
struction of good brick streets will create an increasing de- 
mand for them. And while it may not seriously injure the 
business of the asphalt companies, it will have a tendency 
to lower both the first cost and the maintenance of streets 
constructed by^them. 

Many streets are now opened and paved in a more or less 
expensive manner, where no such outlay should be made, as 
the work is totally wrecked in the subsequent laving of gas 
and water mains, constructing sewers, and making connec- 
tions wnth such lines. Common sense would indicate that 
the order of Avork should be reversed ; that a subgrade should 
be made ; all underground conduits completed and connec- 
tions therewith carried to property lines ; the surface then 
covered with a coating of gravel or broken stone and gravel. 



80 BRICK FOR STREET PAVEMENTS. 

which should be used as a roadway until trenches had be- 
come iirm, and this metal would then remain on which to 
place the foundation for the permanent pavement. Were 
this order of work insisted upon in opening new streets an 
immense saving would be effected. In repaving, the work 
should be done in the same order, suiting the manner of ex- 
ecuting it to the necessities of the case, and the control of 
all of it should be under a single authority, with plans emi- 
nating from one source. When the traffic upon any street, 
or the use of such street demanded it, let such a pavement 
be laid as is suitable to meet the requirements of the case, 
and when it has been put down, keep it clean, in good re- 
pair and open to public use. Upon a very large percentage, 
probably more than two-thirds, of the paved streets in the 
larger cities, and upon nearly all streets requiring pavements 
in the smaller cities and towns, brick will be found to be a 
suitable material to compete with other substances for street 
paving. This is not saying that brick is the ^' coming pave- 
ment." On the contrary brick has got here. If used prop- 
erly it will stay and will be a standard material for paving 
streets. In the great cities where traffic is heavily concen- 
trated and little attention is given to the roaring of the pass- 
ing current, it will never supplant the granite block; in the 
park drive, the clean rolled surface of hard finely broken 
stone will not give way to it ; the fine avenue, where neat- 
ness, order and style must be maintained, will still be pa\ed 
with asphalt, but it is to be hoped that the noisome rotting 
wooden block, and the rattling filthy cobble-stone, will not 
remain to annoy every sense of propriety and slowly murder 
both innocent and guilty by their noxious exhalations. 

Upon nine-tenths of the paved streets occupied by resi- 
dences, retail stores or office buildings, it would be an error 
almost criminal to put down the noisy, untidy granite block, 
and it would be still worse to use the wooden block, as it is 



BRICK FOR STREET PAVEMENTS. 81 

ordinarily laid in this country, while 2^ good brick pavement 

would be quiet, can be kept very clean, and in nearly all such 

cases would last almost a lifetime, with a minimum expense 

for repairs. 

Maintenance. 

The ordinary practice regarding the maintenance of 
street pavements appears to be at variance with established 
methods in any other similar thing. When a line of railway 
has been constructed it is placed in charge of the department 
of maintenance of way, and is kept in proper condition for 
use. When a street has been improved the gay and festive 
plumber, singing as he toils, is legally permitled to dissect (ts 
vitals ; licensed sewer-tappers will disembowel it upon the 
authority of a sovereign department; street railway compa- 
nies will dig it up to adjust their tracks ; the water depart- 
ment will probe it to rearrange their connections, and |>;as 
companies will carve it to erect their lamps. Each will ce- 
place the disturbed material in his own way, and the street- 
cleaning department will haul away such as remains lo<)se 
upon the surface. In the meantime no one looks for, or 
remedies defects in their incipiency, the street having JMst 
been paved is supposed to require no attention, and so long 
as it remains passable without danger to life and limb, is not 
repaired. If a drain becomes clogged no one knows aMy- 
thing about it until the owners of the inundated properties 
file claims for damages, which are promptly referred to the 
engineer and solicitor. If vehicles are wrecked or animals 
crippled the claims filed by owners go to the legal depart- 
ment, and not until the street has been absoluteiy destroyed 
will it receive any attention from the repairing department. 
If it should happen to have been constructed under the 
supervision of officials of an opposite political complexion 
from those now repairing it, money will be lavished upon it 
to show how utterly rotten and useless were the works con- 
8 



82 BRICK FOR STREET PAVEMENTS. 

structed at enormous expense by the other party. Should it 
be some of their own work, it will be easy to show that it 
was honestly constructed, but was ruined by the actions ol* 
other sovereign and independent departments. 

Imagine the effect of placing railways under the control 
of half a dozen independent boards with no executive head, 
their revenues separated into distinct funds with sovereign 
boards to disburse them, each caring mainly that its minutes 
shall record resolutions, ordinances, or references in proper 
sequence and due form; so ^vorded as to guard the rights 
and actions of the board as a body, and show that various 
matters were considered^ and would be acted upon when some 
other department had done something else. Think of any 
corporation conducting any business enterprise upon such 
methods, and cease to wonder why pavements are not kept 
in repair. 

During the first years of the life of a pavement it should 
be carefully watched, and the beginnings of evil to it should 
bo checked, just as a new line of railway will require a 
heavier force of section men than one that, having been 
pi operly maintained, has been longer in use. Expensive re- 
newals may be needed as portions of the structure become 
T^orn by use, but care and watchfulness are of greatest use 
upon new work. And this is just as true of streets as it is 
of any like constructions. Contracts for street construction 
frequently contain provisions requiring the constructor to 
maintain his work for periods of time varying from one to 
five or more years, but the meaning usually given this clause 
l)y the contractor is that, at the expiration of the time 
uamed he shall make such repairs of the portions of his 
w^ork which have not been dug up in the interval by some 
other party as may be designated, and received the retained 
percentage. There is uncertainty about this provision re- 
maining in force for any considerable length of time. En- 



BRICK FOK STREET PAVEMENTS. 88 

terprising attorneys may argue that assessments should be 
made for the cost of construction, and that the expense of 
maintenance should not be assessed, but borne by the corpora- 
tion, and no one can tell what the court will say until it 
speaks in deciding the case as then presented. An etHcient 
force, under experienced, skillful direction, employed in the 
inspection and maintenance of streets would appear to be an 
absolute necessity in every municipality. If such an organi- 
zation exists in any American municipality, it has published 
no report of its services to date. If existing regulations can 
not be bettered, then our form of government as applied to 
municipalities is a failure. 

What is in a ^^ame. 
The title hrick^ as applied to clay products used for street 
paving, would appear to the writer as a misnomer. The 
name ordinarily conveys to the engineer or builder the idea 
of a brittle porous substance, so hungry for moisture that it 
must be saturated before being laid in mortar, solely for the 
preservation of the mortar, so brittle that unless combined 
in masses it has little strength, and in no way suited to with- 
stand the attrition or abrasion of street traffic. When [leo- 
ple propose to use such a substance for paving streets, the 
idea is ridiculed, and they must explain that they are not 
using building brick, but an entirely different substance, 
manufactured by brick makers, and in explaining the matter 
use is made of the other unhappy term, " vitrified brick.'' 
The only clay product suitable for use in paving streets re- 
sembles a tile in more respects than it does a brick, and had 
the name tile been chosen in the place of brick a more cor- 
rect idea would have been conveyed. The first having gone 
forth, however, it may be expedient to concur in the usual 
practice, but it will always be necessary to bear in mind that 
brick as used in street paving is a substance radically differ- 
ent from brick as used in anv other connection. 



84 brick for street pavements. 

Size of Paving Brick. 

A glance at the tables giving dimensions of specimens 
reveals the curious fact that hardly any two manufacturers 
make bricks of the same size. One of the first steps to be 
taken by manufacturers should be the adoption of a stand- 
ard size for street paving bricks. Obviously their preference 
would be to make blocks of about the same dimensions as 
building bricks for both uses. When they make paving 
blocks only, and sell by the square yard, their interest will lie 
in the direction of increased thickness and diminished width. 
A large majority of manufacturers supply material for brick 
masonry as well as for paving, and can assort their output 
without material loss, thus enabling them to supply better 
goods for paving when they are required so to do, without 
suffering the entire loss of the value of such as may be re- 
jected. This, from the manufacturers' standpoint, is the 
greatest argument in favor of making the dimensions of 
paving the same as building brick. 

The users side of the question should be considered. 
The width of the brick or block forms the thickness or 
depth of the pavement. This should not be less than four 
inches. If made much in excess of that depth its cost will 
be increased about in the ratio of the increased depth. In- 
asmuch as four inches will afford ample strength and weight 
to resist the wear of the traffic to which this descrii)tion of 
pavement is suited, there appears to be no reason for mate- 
rially increasing the width beyond that named unless it be to 
meet exceptional cases. In the future, should it appear 
that brick are so perfected as to be able to carry the ex- 
tremely heavy traffic concentrated upon business thorough- 
fares, where granite block pavements are now thought to be 
most suitable, a greater width may be found desirable. The 
length of the brick or block should be about twice its width; 



BRICK FOR STREET PAVExMENTS. 8.') 

its thickness should not exceed its width and may be made 
<3qiial to it, providing such a block can be properly burned. 
The writer does not say that manufacturers can not properly 
dry and burn a brick three or four inches in thickness, but 
he does say that they do not do it. The conditions and the 
experience all indicate failure when massive pieces of clay 
are sought to be burned into bricks or blocks suitable for 
street paving. The nearest approach to success, has been at- 
tained by making the block hollow on the lower side in or- 
der to facilitate burning. For the solid block a thickness of 
two inches, or at most, two and one-half inches, is as great 
as should be attempted. Even where the clays can be melted 
or "vitrified" readily, there is great risk incurred in at- 
tempting to increase the thickness, for such clays usually 
contract greatly, and the outer surface is almost certain to 
be fixed or seared by the intense heat before the inner por- 
tions shall have been so acted upon as to produce the re- 
quired vitrification. As a consequence they come from the 
kiln eitlier insufficiently l)urned, checked with " fire cracks," 
either internal or external ; or, like an ill-shaped casting, so 
affected by internal strains as to have no certain amount of 
strength. Better results are, therefore, likely to be secured 
hy adopting about the building brick dimensions than by at- 
tempting to manufacture blocks of a larger size. Unfor- 
tunately those dimensions have never been determined with 
much accuracy in this country, but they should be, and then 
let manufacturers vary the dimensions of their molds as the 
contractility of the clays vary, so that bricks of equal hard- 
ness shall be of like dimensions. 

It may be argued that the increased number of joints in 
a given area, caused b\' the thinner block, constitute an ele- 
ment of weakness and should, therefore, be avoided. The 
defect is more imaginary than real, since the proposition can 



80 ■ BRICK FOR STREET PAVEMENT.-. 

not be true if made general. The perfect pavement would 
become one without joints, which is impracticable unless 
made of a substance sufficiently yielding or elastic to afford 
secure footing for animals, which practically makes it a 
surface of innumerable joints. An advantage claimed for 
brick pavements is said to be the fact that they can be so 
closely laid, and the joints so completely tille'd, that, while 
they furnisli secure footing for animals, they are so smooth 
as to be quiet, and so impervious as to be cleanly. If this 
be true, the additional number of joints is not objection- 
able. They are not an element of weakness, since the load 
must in any case be carried by the foundation, and the up- 
per and lower surfaces being equal, the Aveight transmitted 
by the brick will be as its area. Should the surface of the 
fouridation be uneven, the smaller block is less liable to be 
tilted by an unequal pressure than the larger one. AVithin 
reasonable limits, therefore, the safe course to pursue w^ould 
undoubtedly lie in the direction of the thinner blocks; or, 
in other words, to adopt a standard size for paving blocks 
corresponding with building brick dimensions. 



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028 145 881 4 



